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Ossifying fibroma is a fibro-osseous lesion of the jaw and usually occurs as a single lesion. Little is known about ossifying fibromas, which occur as a manifestation of hyperparathyroidism-jaw tumor syndrome (HPT-JT), an autosomal dominant disorder. We experienced a patient with HPT-JT who had ossifying fibromas on both sides of the mandible. A 32-year-old female was referred to our department because of swelling on the right side of the mandible. She had a history of parathyroid adenomas and endometrial hyperplasia; however, there was no family history of parathyroid, mandibular, or renal lesions. She was diagnosed with recurrent parathyroid adenoma close to the time of her visit to our department. A biopsy revealed that the jaw lesion was an ossifying fibroma, and genetic testing revealed HPT-JT. She underwent surgery for the parathyroid and mandibular lesions and is currently undergoing follow-up. Accurate diagnosis of HPT-JT is important because it is an inherited condition and is associated with a high incidence of parathyroid carcinoma. This case indicates that cooperation among multiple medical care departments is essential for proper diagnosis and treatment of HPT-JT.

Primary hyperparathyroidism is a relatively common endocrine disorder, affecting 7 out of 1,000 adults. The median age at onset is the 6th decade of life. Our objective was to present a young patient with primary hyperparathyroidism who has a positive CDC73 mutation. A 23-year-old woman was evaluated for hypercalcemia that was found after surgery for bilateral ovarian cyst removal. Her family history included multiple family members with nephrolithiasis. The physical examination revealed a well-appearing Caucasian woman with no palpable neck mass. The laboratory results showed serum calcium at 11.7 mg/dL (ref. 8.4–10.2), ionized calcium at 1.44 mmol/L (ref. 1.12–1.32), and serum PTH at 192 pg/mL (ref. 11–65). A technetium-99 sestamibi scan revealed focal uptake inferior to the left thyroid lobe. Thyroid ultrasound showed a left parathyroid adenoma. The patient subsequently underwent left inferior parathyroidectomy, which confirmed parathyroid adenoma, with resultant normalization of serum calcium and PTH levels. Due to her young age at diagnosis, genetic testing was performed, which revealed a mutation of CDC73. Although penetrance and expression are variable, the CDC73 mutation is associated primarily with hyperparathyroidism-jaw tumor syndrome, familial isolated hyperparathyroidism, and sporadic parathyroid carcinoma. This patient currently has no evidence of jaw, uterine or renal tumors on screening imaging. Given the potential impact of inheritable neoplasia, all young patients with unexplained hyperparathyroidism should be considered for genetic screening.

Background/purpose Hyperparathyroidism-jaw tumor syndrome is a rare autosomal dominant disease characterized by parathyroid tumors and ossifying fibroma of the jaw. Disease-causing mutations have been localized in the tumor suppressor gene CDC73. This study is designed to highlight the importance of genetic testing in the diagnosis of ossifying fibroma related to this syndrome. Materials and methods The Clinical, histopathological, radiographical, familial and genetic features of 24 patients with Hyperparathyroidism-jaw tumor syndrome were collected by searching the electronic literature PubMed, Medline, Embase, and Science Direct databases combining the MeSH heading terms “Hyperparathyroidism jaw tumor syndrome”, with the words “Ossifying fibroma” and “CDC73”. The collected features were simply assessed and analyzed. Results The average age was 28.68 years old (age range 10–66), with 12 male and 12 female patients (1:1 M/F ratio). Hyperparathyroidism results from parathyroid adenoma in 16/24 cases (66.666%) and parathyroid carcinome in 5/24 (20.833%). Bone pathology occurred most often in the mandible (16/24 cases; 66.666%), while 5/24 cases were in the maxilla (20.883%) and 3 cases in both (12.5%). In 5/24 cases, ossifying fibroma was the first to occur before hypercalcemia. Genetic mutation of CDC73 were positive in 19/24 cases (79.166%). Conclusion Since the jaw lesions in Hyperparathyroidism-jaw tumor syndrome could proceed the cardinal signs of hyperparathyroidism, its accurate diagnosis needs to depend on clinical, histological, radiographical, family history and most of all the genetic testing for CDC73 gene.

While somatic disruptive mitochondrial DNA (mtDNA) mutations that severely affect the respiratory chain are counter-selected in most human neoplasms, they are the genetic hallmark of indolent oncocytomas, where they appear to contribute to reduce tumorigenic potential. A correlation between mtDNA mutation type and load, and the clinical outcome of a tumor, corroborated by functional studies, is currently lacking. Recurrent familial oncocytomas are extremely rare entities, and they offer the chance to investigate the determinants of oncocytic transformation and the role of both germline and somatic mtDNA mutations in cancer. We here report the first family with Hyperparathyroidism-Jaw Tumor (HPT-JT) syndrome showing the inherited predisposition of four individuals to develop parathyroid oncocytic tumors. MtDNA sequencing revealed a rare ribosomal RNA mutation in the germline of all HPT-JT affected individuals whose pathogenicity was functionally evaluated via cybridization technique, and which was counter-selected in the most aggressive infiltrating carcinoma, but positively selected in adenomas. In all tumors different somatic mutations accumulated on this genetic background, with an inverse clear-cut correlation between the load of pathogenic mtDNA mutations and the indolent behavior of neoplasms, highlighting the importance of the former both as modifiers of cancer fate and as prognostic markers.

Primary hyperparathyroidism (PHPT) is a rare endocrine disease in the pediatric population. Sporadic parathyroid adenomas remain the most common cause of pediatric PHPT. Parathyroid carcinoma (PC) is an extremely rare cause of pediatric PHPT. We report a 16-year-old boy presenting with a nonhealing fragility fracture of the right leg along with florid features of rickets. Examination revealed a neck mass, mimicking a goiter. Biochemical findings were consistent with PHPT. Imaging was suggestive of a right inferior parathyroid mass infiltrating the right lobe of thyroid. The patient underwent en bloc surgical excision of the parathyroid mass along with the right lobe of thyroid. Histopathology was suggestive of a PC. He achieved biochemical remission with normalization of serum calcium and parathyroid hormone levels. At follow-up, there was no biochemical or imaging evidence of recurrence or metastasis. Genetic analysis revealed heterozygous germline deletion of CDC73. An extensive literature search on PC was conducted, with an emphasis on the pediatric population. Thirteen cases of pediatric PC were identified. The median age of presentation was 13 years; there was no sex predilection. All cases were symptomatic; 31% had a visible neck mass. The median serum calcium and intact parathyroid hormone levels were 14.3 mg/dL and 2000 pg/mL, respectively. All patients underwent surgical excision, with 27% showing metastatic relapse. Our findings indicate that the preoperative features that could point toward a diagnosis of PC in a child with PHPT are a tumor size of >3 cm, thyroid infiltration on imaging, and severe hypercalcemia at presentation.

We described the phenotype of a large 4-generation family with Hyperparathyrodism-Jaw Tumor syndrome (HPT-JT) associated with a rare deletion of exon 3 of the CDC73 gene. We collected medical, genetic data on 24 family members descended from a common ancestor carrying a heterozygous deletion of exon 3. Thirteen carried the deletion, the penetrance was estimated at 50% at 40 years. Seven patients (39 ± 14.5 years) presented with HPT which could start at 13. Median plasmatic calcium and PTH levels were 3.13 ± 0.7 mmol/L and 115 ± 406 pg/ml, respectively. Kidney disease related to hypercalcemia were present in 57.1% of patients. All seven patients underwent surgery to remove a single parathyroid adenoma. One recurrence occurred 7 years post-surgery. No parathyroid carcinoma has been found to date. We found two atypical parathyroid adenomas. We described an additional somatic variant in exon 1 of gene CDC73 in two tumors. Jaw tumors were not necessarily associated with hyperparathyroidism, as shown in one case. Two kidney cysts were also reported. Variable phenotype expressivity was emphasized by clinical presentations in 2 monozygotic twins: acute hypercalcemia, kidney failure and ossifying fibroma in one twin, versus normocalcemic parathyroid adenoma in the other one. We report a family carrier of a deletion of exon 3 of the CDC73 gene. This is characterized by a high level of hypercalcemia, deleterious kidney effects and atypical parathyroid adenomas without carcinomas. Onset and intensity of HPT remain unpredictable. The additional somatic mutation found in the parathyroid tumor could lead to these phenotypical variations.

Hyperparathyroidism-jaw-tumor syndrome (HPT-JTS) is a rare autosomal dominant disorder. A typical manifestation of HPT-JTS is the association of jaw-ossifying fibroma with primary hyperparathyroidism. Due to its rarity and diversity in its manifestations, it is a challenging diagnosis. A 33-year-old woman was referred due to painful swelling of the right maxilla suggestive of malignancy. The clinical presentations were not conclusive until she underwent F18-fluorodeoxyglucose positron emission tomography/computed tomography (F18-FDG PET/CT). F18-FDG PET/CT proved to be a useful tool to assist the clinicians in visualizing the "bigger picture" and, therefore all manifestation as pieces of "one puzzle."

ContextAtypical parathyroid adenomas (APAs) are neoplasms with uncertain malignant potential but lack unequivocal histological signs of malignancy.ObjectiveThis work aims to retrospectively evaluate the clinical and biochemical profiles of patients with APA, the outcome after parathyroidectomy (PTX), and the presence of CDC73 germline and somatic mutations.MethodsThis monocentric study was conducted on consecutive patients undergoing PTX for primary hyperparathyroidism (PHPT) between June 2000 and December 2020. Fifty-eight patients with a confirmed histopathological diagnosis of APA, and age- and sex-matched controls with parathyroid adenoma (PA) were also included.ResultsFifty-four patients had sporadic PHPT and 4 had familial isolated hyperparathyroidism (FIHP). Thirty-four patients (59%) had symptomatic disease. Serum calcium and parathyroid hormone (PTH) levels were significantly higher in symptomatic compared to asymptomatic patients (P = .048 and .008, respectively). FIHP patients were younger than their sporadic counterparts (30 ± 17 years vs 55 ± 13 years). APA patients had significantly higher serum calcium and PTH levels and lower 25-hydroxyvitamin D concentration, bone mineral density, and T score at one-third distal radius compared to those with PA. Four of 56 APA patients displayed a CDC73 germline mutation. No somatic CDC73 mutation was identified in 24 tumor specimens. The mean follow-up after surgery was 60 ± 56.4 months. All but 6 patients (90%), 5 with apparently sporadic PHPT and 1 with FIHP, were cured after surgery.ConclusionThe large majority of patients with APA, despite a moderate/severe phenotype, have a good prognosis. Germline CDC73 mutation–positive patients had a higher rate of persistent/recurrent disease. CDC73 gene alterations do not seem to have a relevant role in the tumorigenesis of sporadic APA.

Purpose: Previously in 1987, a 21-year-old-male was diagnosed with primary hyperparathyroidism (PHPT) when a right inferior parathyroid adenoma was removed. PHPT recurred after three and six years and on both occasions was cured by resection of parathyroid adenomas. At 52-years-of-age, the patient developed a late-onset hypoparathyroidism (HP), even though postsurgical HP typically occurs as a transient or permanent form soon after neck surgery. The purpose of this work was to report the follow-up of the patient and to review prior cases of late-onset postsurgical HP.\ud \ud Methods: Prior cases of late-onset postsurgical HP were searched and reviewed focusing on clinical and biochemical features.\ud \ud Results: The patient’s asymptomatic hypocalcemia with total serum calcium at 8.2 mg/dL was initially documented in September 2018; PTH was inappropriately low at 15 ng/mL. In\ud February 2020, a mild hypocalcemia was confirmed with low-normal PTH at 15 ng/mL. Autoimmune and familial causes of HP were ruled out including the presence of stimulating autoantibodies against calcium-sensing receptor. Instead, a progressive damage or atrophy of the parathyroid gland(s) ensuing years after surgery is believed to have led to the patient’s hypocalcemia. All 19 previously reported cases of late-onset postsurgical HP occurred after thyroid surgery, with no examples of the condition being found following parathyroidectomy.\ud \ud Conclusions: The case highlights the rare occurrence of late-onset postsurgical HP in a patient who had had multiple parathyroidectomies for PHPT. Thus, monitoring serum calcium,\ud phosphate and PTH during follow-up of such patients is recommended.

© 2018 The Author(s). Published by Wolters Kluwer Health, Inc. The gene CDC73 (previously known as HRPT2) encodes the protein parafibromin. Biallelic mutation of CDC73 is strongly associated with malignancy in parathyroid tumors. Heterozygous germline mutations cause hyperparathyroidism jaw tumor syndrome,which is associated with a high life-time risk of parathyroid carcinoma. Therefore loss of parafibromin expression by immunohistochemistry may triage genetic testing for hyperparathyroidism jaw tumor syndrome and be associated with malignant behavior in atypical parathyroid tumors. We share our experience that parafibromin-negative parathyroid tumors show distinctive morphology. We searched our institutional database for parathyroid tumors demonstrating complete loss of nuclear expression of parafibromin with internal positive controls. Forty-three parafibromin-negative tumors from 40 (5.1%) of 789 patients undergoing immunohistochemistry were identified. Thirty-three (77%) were external consultation cases; the estimated incidence in unselected tumors was 0.19%. Sixteen (37.2%) fulfilled World Health Organization 2017 criteria for parathyroid carcinoma and 63% had serum calcium greater than 3mmol/L. One of 27 (3.7%) noninvasive but parafibromin-negative tumors subsequently metastasized. Parafibromin-negative patients were younger (mean, 36 vs. 63 y; P

Background. Primary hyperparathyroidism usually occurs secondary to parathyroid adenoma, multiglandular hyperplasia, or parathyroid carcinoma. The patients usually present with incidentally discovered high calcium level and systemic or skeletal manifestations. In young patients with primary hyperparathyroidism, familial syndromes including multiple endocrine neoplasia types 1, 2, and 4 and hyperparathyroidism jaw tumor syndrome should be considered. Case Description. We present a case of a 22-year-old Sri Lankan woman who presented with femur fractures in a background of childhood nephroblastoma and maxillary fibro-osseous tumor. The patient had biochemical parameters suggestive of primary hyperparathyroidism with a parathyroid mass. The histology following excision of the mass revealed a parathyroid adenoma. Based on the associated clinical manifestations, hyperparathyroidism jaw tumor syndrome was suspected, and genetic studies reported a positive CDC73 mutation with a whole-gene deletion of exon 1–17. Conclusion. Hyperparathyroidism jaw tumor syndrome is an important diagnosis to consider in a young patient presenting with classic clinical features due to the risk of malignancy, familial involvement, and need to monitor for progressive systemic manifestations. As this is a rare disease, it can often be missed due to low degree of suspicion and the ability of the jaw tumor to mimic a metastatic deposit.

Primary hyperparathyroidism (PHPT) is sporadic in the majority of cases. Hereditary forms of PHPT are rarer, however, they are of particular interest because they allow a deeper understanding of pathogenesis of parathyroid neoplasia. Hereditary forms of PHPT include multiple endocrine neoplasia type 1 (MEN-1), type 2A (MEN-2A), type 4 (MEN-4), hyperparathyroidism-jaw tumour syndrome (HPT-JT), variants of familial hypocalciuric hypercalcemia (FHH) and familial isolated hyperparathyroidism (FIHP). Mutations in the following genes cause the development of MEN-1, MEN-2A, MEN4, HPT-JT: MEN1, RET, CDKN1B, CDC73, respectively. Variants of FHH are caused by mutations in CASR, AP2S1, GNA11. Gene(s) responsible for the development of the majority of FIHP cases remain unknown. Identification of hereditary forms of PHPT is important for patients and their first-degree relatives, as it allows defining the necessity of screening to reveal other components of the syndrome, in some cases determines the surgical approach to PHPT, and the risk of development of the disease in offsprings. This article provides information on hereditary syndromes associated with PHPT and special features of PHPT in each syndrome.

Hyperparathyroidism-jaw tumor (HPT-JT) is an autosomal dominant disorder responsible for benign and/or malignant tumors. Affected women often present life-threatening menorrhagia that leads to the identification of uterine tumors, and experience miscarriages and infertility. Overall though, fewer data concerning gynecological pathologies related to HPT-JT syndrome are available. We report the case of a 32-year-old woman with HPT-JT syndrome, referred for recurrent vaginal bleeding, with a history of repeated endometrial polyps and infertility. We also review the literature that explores medical options for these women.

Hyperparathyroidism jaw tumor syndrome is a rare syndrome with features of primary hyperparathyroidism, ossifying fibromas of the jaw, and parathyroid carcinoma. Certain features of hyperparathyroidism jaw tumor syndrome may suggest an underlying parathyroid carcinoma as illustrated in the case reported here. High index of suspicion for parathyroid carcinoma will require radical surgery in the first attempt and avoid re-do surgery.

We herein report the case of a young woman who was diagnosed with primary hyperparathyroidism and in whom genetic testing confirmed a diagnosis of hyperparathyroidism-jaw tumor syndrome. Familial hyperparathyroidism was suspected based on the patient's young age at the onset of the disease. Thus, genetic testing was performed. It showed a germline mutation in the HRPT2/CDC73 gene and confirmed the diagnosis of hyperparathyroidism-jaw tumor syndrome. Total parathyroidectomy was performed to prevent recurrence. In patients with early-onset hyperparathyroidism, genetic testing should be considered to facilitate the selection of a proper surgical procedure based on the consideration of future life expectancy.

Background Primary hyperparathyroidism (PHPT) is a relatively rare disorder among children, adolescents and young adults. Its development at an early age is suspicious for hereditary causes, though the need for routine genetic testing remains controversial. Objective To identify and describe hereditary forms of PHPT in patients with manifestation of the disease under 40 years of age. Design We enrolled 65 patients with PHPT diagnosed before 40 years of age. Ten of them had MEN1 mutation, and PHPT in them was the first manifestation of multiple endocrine neoplasia type 1 syndrome. Methods The other fifty-five patients underwent next-generation sequencing (NGS) of a custom-designed panel of genes, associated with PHPT (MEN1, CASR, CDC73, CDKN1A, CDKN1B, CDKN1C, CDKN2A, CDKN2C, CDKN2D). In cases suspicious for gross CDC73 deletions multiplex ligation-dependent probe amplification was performed. Results NGS revealed six pathogenic or likely pathogenic germline sequence variants: four in CDC73 c.271C>T (p.Arg91*), c.496C>T (p.Gln166*), c.685A>T (p.Arg229*) and c.787C>T (p.Arg263Cys); one in CASR c.3145G>T (p.Glu1049*) and one in MEN1 c.784-9G>A. In two patients, MLPA confirmed gross CDC73 deletions. In total, 44 sporadic and 21 hereditary PHPT cases were identified. Parathyroid carcinomas and atypical parathyroid adenomas were present in 8/65 of young patients, in whom CDC73 mutations were found in 5/8. Conclusions Hereditary forms of PHPT can be identified in up to 1/3 of young patients with manifestation of the disease at CDC73 mutations.

Hyperparathyroidism-jaw tumor syndrome (HPT-JT) is a rare autosomal dominant cause of familial hyperparathyroidism associated with benign, ossifying fibromas of the maxillofacial bones and increased risk of parathyroid carcinoma. The putative tumor suppressor gene CDC73 has been implicated in the syndrome, with a multitude of inactivating mutations identified; however, HPT-JT due to large-scale deletion of the chromosomal region containing the gene is exceedingly rare, and the clinical significance of this variant remains unclear. We report the case of a 32-year-old woman with a history of mandibular ossifying fibroma who presented with primary hyperparathyroidism and was found to harbor a large-scale, germline deletion on chromosome 1q31, including the CDC73 locus. HPT-JT is associated with loss of function of the putative tumor suppressor gene CDC73. Over 100 mutations and small insertions/deletions have been identified within the gene, the majority of which result in premature truncation of the parafibromin protein product. We report a case of HPT-JT associated with a large chromosomal deletion (4.1 Mb) encompassing the CDC73 gene locus. In the future, molecular testing in this autosomal dominant disorder should use techniques that allow for the detection of large-scale deletions in addition to the more commonly observed mutations and smaller-scale copy number alterations. Further investigation is needed to determine whether HPT-JT associated with a large-scale deletion carries increased risk of malignancy relative to the more common truncating mutations and what the implications are for genetic counseling., A case of hyperparathyroidism-jaw tumor syndrome associated not with a point mutation, but rather with a large chromosomal deletion encompassing the CDC73 gene locus.

Hyperparathyroidism-jaw tumor syndrome (HPT-JT) is a rare disease caused by CDC73 germline mutations, with familial primary hyperparathyroidism (pHPT), ossifying jaw tumors, genito-urinary neoplasms. The present study was aimed at determining the long-term postoperative outcome of parathyroidectomy in HPT-JT. A retrospective analysis of a single-center series of 20 patients from five unrelated HPT-JT families undergoing parathyroid surgery was performed. Pathology confirmed a single-gland involvement in 95% of cases at onset. Parathyroid carcinoma occurred in three patients undergoing en-bloc parathyroidectomy and thyroid lobectomy: parathyroid benign lesions in 17 patients undergoing subtotal parathyroidectomy for evident multiglandular involvement (n = 1) or selective parathyroidectomy for single-gland involvement (n = 16), during bilateral (n = 13) or targeted unilateral neck exploration (n = 7). At a median overall follow-up of 16 years (range 2.5–42), patients with parathyroid carcinoma had a persistent/recurrent disease in 66.6%; patients with benign lesions had recurrent pHPT in 23.5% after a prolonged disease-free period; recurrent benign pHPT occurred slightly more often in cases of discordant preoperative localization (60% vs 9%; p = 0.06). pHPT in HPT-JT is generally characterized by a benign and single-gland involvement, with a relatively increased risk of malignancy (15%). Parathyroid carcinoma needs extensive surgery because of high risk of permanent/recurrent disease (66.6%). In benign involvement, targeted unilateral exploration with selective parathyroidectomy may be effective in cases of concordant single-gland localization at preoperative localization imaging techniques. Bilateral neck exploration with subtotal parathyroidectomy might be preferred in cases of negative or discordant preoperative localization, because of the increased risk of multiglandular involvement and long-term recurrences (23.5%).

Hyperparathyroidism-jaw tumor (HPT-JT) syndrome is an autosomal dominant disorder characterized by parathyroid tumors in association with fibro-osseous jaw tumors and uterine and renal lesions. HPT-JT syndrome is caused by germline mutations of the cell division cycle 73 (CDC73) gene that encodes the parafibromin, a 531-amino acid protein with antiproliferative activity. Primary hyperparathyroidism is the main finding of HPT-JT syndrome, usually caused by a single-gland parathyroid involvement (80% of cases), at variance with other variants of hereditary hyperparathyroidism, in which a multiglandular involvement is more frequent. Moreover, parathyroid carcinoma may occur in approximately 20% of cases. Surgery is the treatment of choice for primary hyperparathyroidism, but the extent of surgery remains controversial, varying between bilateral neck and focused exploration, with subtotal or limited parathyroidectomy. Recently, more limited approaches and parathyroid excisions have been suggested in order to decrease the risk of permanent hypoparathyroidism, the main surgical morbidity following more extensive surgical approaches. Ossifying fibromas of the mandible or maxilla may present only in a minority of cases and, even if benign, they should be surgically treated to avoid tumor growth and subsequent functional limitations. Benign and malignant uterine involvement (including leiomyomas, endometrial hyperplasia, adenomyosis, multiple adenomyomatous polyps, and adenosarcomas) is the second most common clinical feature of the syndrome, affecting more than 50% of CDC73-carrier women. Genetic testing should be performed in all family members of affected individuals, in young patients undergoing surgery for primary hyperparathyroidism, or in presence of other associated tumors, allowing early diagnosis and prompt treatment with more tailored surgery. Moreover, CDC73 mutation carriers should be also periodically screened for primary hyperparathyroidism and the other associated tumors. The present review was aimed to summarize the main clinical features of HPT-JT syndrome, focusing on genetic screening and surgical treatment, and to revise the available literature.

Background: Hyperparathyroidism-jaw tumor syndrome (HPT-JT) is a rare autosomal dominant disease, caused by mutations in the CDC73 gene, characterized by parathyroid tumors in association with fibro-osseous lesions of the mandible or maxilla. The occurrence of renal cysts or tumors, uterine and thyroid tumors has been reported. The association with other neoplastic lesions has been described, but its meaning and frequency are not well established. Clinical Case: A 48-year-old Roma woman was admitted to our hospital due to severe abdominal pain and constipation. She had a past history of kidney stones with several episodes of acute renal colic and had been recently diagnosed with colon cancer. Her family history was positive for colon cancer. Disease staging suggested the presence of liver metastases and multiple lytic lesions of the axial skeleton, pelvis and femurs. Laboratory investigation disclosed high calcium levels (15 mg/dL) and cancer associated hypercalcemia was suspected. However, PTH was markedly elevated (2979 pg/mL), in favor of a parathormone dependent cause. Further imaging procedures showed a heterogeneous mass, posterior to the right thyroid lobe and bone lesions on the left mandible, likely to correspond to brown tumors. Once the hypercalcemia was controlled, she was submitted to parathyroidectomy and right thyroid lobectomy plus sigmoidectomy and liver biopsy. The histology revealed an atypical parathyroid adenoma with 3,5 cm and papillary thyroid cancer with 1,2 cm, as well as colon adenocarcinoma metastatic to the liver. Postoperatively, the patient developed a hungry bone syndrome needing adequate treatment. Two months after surgery, the patient initiated chemotherapy for colon cancer. Screening for germline mutations in the CDC73 gene (formerly HRPT2) was positive for a deletion (c.765_766delTG/p.Val256LysX10). Conclusions: Hypercalcemia in a patient with malignant disease may be independent of malignancy. In the patient presented herein her past history of kidney stones and the involvement of the mandible were highly suggestive of HPT-JT. Missing the diagnosis would negatively impact in the patient′s prognosis and in the management of her family. Further clinical and genetic studies are ongoing trying to clarify whether the patient has two inherited conditions or a phenotype of HPT-JT including colon cancer.

The article describes two clinical cases of severe primary hyperparathyroidism (PHPT) caused by parathyroid carcinoma in young female patients who underwent molecular genetic testing to rule out the hereditary forms of PHPT. In both patients, heterozygous germline nonsense mutations of tumor suppressor gene CDC73 encoding parafibromin (p.R91X and p.Q166X) were identified using next-generation sequencing with Ion Torrent Personal Genome Machine (Thermo Fisher Scientific - Life Technologies, USA). It is the first description of CDC73 mutations in Russia, one of the mutations is described for the first time in the world. Identification of germline mutations in the CDC73 gene in patients with PHPT necessitates regular lifelong screening for other manifestations of hyperparathyroidism-jaw tumor syndrome (HPT-JT), PHPT recurrence due to parathyroid carcinoma as well, and identification of mutation carriers among first-degree relatives.Представлено описание двух клинических случаев первичного гиперпаратиреоза (ПГПТ) тяжелого течения у молодых больных раком околощитовидной железы, которым проведено молекулярно-генетическое исследование для исключения наследственных форм ПГПТ. Методом высокопроизводительного параллельного секвенирования на полупроводниковом секвенаторе Ion Torrent Personal Genome Machine (Thermo Fisher Scientific - Life Technologies, США) у обеих пациенток выявлены герминальные гетерозиготные нонсенс-мутации в гене - супрессоре опухолевого роста CDC73, кодирующем белок парафибромин: p.R91X и p.Q166X. В России мутации в указанном гене описываются впервые, одна из мутаций описывается впервые в мире. Выявление герминальных мутаций в гене CDC73 у пациентов с ПГПТ требует пожизненного регулярного профилактического обследования для ранней диагностики компонентов синдрома гиперпаратиреоза с опухолью челюсти (hyperparathyroidism-jaw tumor syndrome - HPT-JT), рецидива ПГПТ после хирургического вмешательства, в том числе вследствие рака околощитовидной железы, а также позволяет выявить носителей мутаций среди родственников первой линии родства.Представлено описание двух клинических случаев первичного гиперпаратиреоза (ПГПТ) тяжелого течения у молодых больных раком околощитовидной железы, которым проведено молекулярно-генетическое исследование для исключения наследственных форм ПГПТ. Методом высокопроизводительного параллельного секвенирования на полупроводниковом секвенаторе Ion Torrent Personal Genome Machine (Thermo Fisher Scientific — Life Technologies, США) у обеих пациенток выявлены герминальные гетерозиготные нонсенс-мутации в гене — супрессоре опухолевого роста CDC73, кодирующем белок парафибромин: p.R91X и p.Q166X. В России мутации в указанном гене описываются впервые, одна из мутаций описывается впервые в мире. Выявление герминальных мутаций в гене CDC73 у пациентов с ПГПТ требует пожизненного регулярного профилактического обследования для ранней диагностики компонентов синдрома гиперпаратиреоза с опухолью челюсти (hyperparathyroidism-jaw tumor syndrome — HPT-JT), рецидива ПГПТ после хирургического вмешательства, в том числе вследствие рака околощитовидной железы, а также позволяет выявить носителей мутаций среди родственников первой линии родства.

When primary hyperparathyroidism (PHPT) is diagnosed in a young patient in the absence of other clinical manifestations differential diagnosis between a sporadic form of PHPT and PHPT as the first manifestation of one of hereditary syndromes may be challenging. Diagnosis of sporadic or hereditary PHPT determines the extent of surgical intervention, a strategy for further observation and treatment, and the need for examination and treatment of first-degree relatives. Aim of the study — to determine genetic characteristics of PHPT with manifestation at a young age (A. In 4 (4/40, 10%) patients we revealed germline heterozygous mutations in CDC73 gene: 3 nonsense mutations in patients with parathyroid carcinoma — in exon 3 p.R91X, exon 6 p.Q166X, exon 7 p.R229X, and 1 missense mutation in a patient with parathyroid hyperplasia in exon 8 p.R263C. Conclusions. In the majority of cases (75%) PHPT in young patients without positive family history is sporadic. Search for germline mutations in the genes, leading to development of hereditary forms of PHPT (first of all in MEN1 and CDC73), is appropriate in young patients with positive family history, or when positive family history may be suspected, and in patients with parathyroid carcinoma. In the majority (75%) of FIHP cases search for other, probably yet unknown, genes is necessary.

Context Hyperparathyroidism-jaw tumour (HPT-JT) syndrome is a rare autosomal dominant cause of familial hyperparathyroidism associated with ossifying fibromas (OF) of the maxillofacial bones and increased risk of parathyroid carcinoma, caused by inactivating germline mutation of the cell division cycle 73 (CDC73) gene. Objective To report the first Romanian family with HPT-JT and genetic screening of CDC73 gene. Subjects and methods Mutational analysis of the CDC73 gene and genetic screening of the family of a proband with HPT-JT. Histological diagnosis of parathyroid tumors (WHO criteria) and immunohistochemistry (parafibromin) were performed. Results Three of the six screened family members had evidence of PHPT and surgically proven parathyroid tumours. Two of the three affected members had parathyroid carcinomas and one had two parathyroid adenomas. Genetic screening of CDC73 gene revealed that 4 of 6 patients showed a heterozygous germline deletion of one nucleotide: c.128-IVS1+1 delG. All the three affected patients, resulted to be carriers of the CDC73 mutation, but each one bearing a different CDC73 polymorphism. Conclusions We identified a new CDC73 germline mutation in a Romanian family of HPT-JT. Analysis of clinical phenotypes in the four mutated individuals confirmed the incomplete penetrance and the variable clinical expression of the disease.

Parathyroid carcinoma (PC) is a rare neoplasm with a high rate of recurrence and an indolent course. It is frequently functional, causing nearly 1% of the cases of primary hyperparathyroidism (HPT), and in some cases, it may be complicated by brown tumors, mimicking bone metastases. Synchronous parathyroid and papillary thyroid carcinomas are rare. We present a patient with HPT due to PC, misdiagnosed at first evaluation, which exhibited multiple hypermetabolic lytic lesions in the skeleton, suggesting bone metastases. Their regression after PTH reduction suggested the diagnosis of brown tumors due to severe HPT. Given the persistence of HPT, the patient underwent a number of neck surgeries, and a papillary thyroid microcarcinoma with a nodal metastasis was diagnosed. A genetic test discovered a previously unreported mutation of the CDC73 (HRPT2) gene, codifying for parafibromin and resulting in a premature stop codon (c.580A>Tp.Arg194). Because of the persistence of HPT, cinacalcet therapy was started in order to control hypercalcemia. This is a very unusual patient with a newly discovered variant of the CDC73 gene and a phenotype characterized by recurrent PC, brown tumors, and N1a metastasized thyroid carcinoma. The present case confirms that PC may not exhibit clear malignant properties at first assessment, contributing to inadequate initial surgical treatment. Although infrequently, PC can be associated with papillary thyroid cancer. The diagnosis of brown tumor should be considered in patients with severe HPT and multiple destructive bone lesions mimicking metastases on PET/CT imaging.

Primary hyperparathyroidism, a common endocrine disorder, is associated with familial disease in about 10% of cases. These syndromes include multiple endocrine neoplasia types 1, 2A and 4 (MEN1, MEN2A, MEN4), familial isolated hyperparathyroidism (FIHP), and the hyperparathyroidism jaw tumor (HPT-JT) syndrome. HPT-JT syndrome, an autosomal dominant disease with incomplete penetrance, results from a germline inactivating mutation in the HRPT2 gene. HPT-JT manifests with about 20% of patients having multiple enlarged parathyroid glands and/or parathyroid carcinoma. Furthermore, 28% of patients will have a recurrence during follow-up. Since these patients have a high rate of multiple enlarged parathyroid glands, parathyroid carcinoma, and recurrence, it is controversial as to what is the optimal initial surgical approach for parathyroidectomy. Clinical evidence for the optimal initial surgical approach for HPT-JT syndrome is limited to case series and retrospective small cohort studies. Furthermore, there is scant data on the clinical utility of localization studies to select the optimal operative approach. Only one study reported the results of localization studies and showed a lack of benefit due to high rates of multigland disease that would have been missed if a focused parathyroidectomy approach was used. Given the high rates of multigland disease, parathyroid carcinoma, risk of recurrence, and the possibility of missing additional enlarged glands not seen on preoperative localizing studies, bilateral neck exploration with identification of all four glands and removal of enlarged glands would be the best surgical approach given our current knowledge.

Hyperparathyroidism-jaw tumor syndrome (HPT-JT) is a rare autosomal dominant hereditary tumor syndrome characterized by synchronous or metachronous occurrence of primary hyperparathyroidism (PHPT), ossifying fibroma of the maxilla and/or mandible, renal tumor and uterine tumors. Early diagnosis of this syndrome is essential because it is associated with increased risk of parathyroid cancer. A 30-year-old man with urolithiasis had severe hypercalcemia (15.0 mg/dL after correction) induced by inappropriate parathyroid hormone (PTH) secretion (intact PTH 1390 pg/mL), indicating severe PHPT. An underlying parathyroid tumor was surgically removed and was histologically confirmed to be an adenoma. However, PHPT due to another parathyroid tumor reoccurred two years after the surgery. Although no HPT-JT-associated manifestations other than PHPT were detected, HPT-JT was strongly suspected based on the exclusion of multiple endocrine neoplasia (MEN) and the young age of disease occurrence. Genetic analysis revealed a novel nonsense mutation (p.Arg91X; c.271C>T) in exon 3 of the causative gene, CDC73, which encodes the tumor suppressor protein parafibromin. The residual parathyroid glands were all removed without autotransplantation of parathyroid gland taking into consideration prospective parathyroid carcinogenesis. The resected parathyroid tumor was also an adenoma. The present case highlights that HPT-JT should be considered and CDC73 mutation analysis should be performed, especially in cases of early-onset PHPT, recurrent PHPT, PHPT with polyglandular parathyroid involvement, and PHPT presenting with severe hypercalcemia even if there is no positive family history.

Background Hyperparathyroidism-jaw tumor syndrome (HPT-JT) is a rare autosomal dominant disease secondary to germline inactivating mutations of the tumor suppressor gene HRPT2/CDC73. The aim of the present study is to determine the optimal surgical approach to parathyroid disease in patients with HPT-JT.

Germline genetic tests can be extremely helpful for clinical diagnosis of patients and their families when a known deleterious change is found, but there are many reasons why gene testing and interpretation is not straightforward. This chapter pertains to monogenic conditions in which the genetic contribution to a parathyroid disorder is well-established. These disorders include: familial hypocalciuric hypercalcemia, neonatal severe hyperparathyroidism, hyperparathyroidism-jaw tumor syndrome and parathyroid carcinoma and multiple endocrine neoplasia types 1, 2, and 4.

Familial hyperparathyroidism occurs in a handful of genetic syndromes including Multiple Endocrine Neoplasia (MEN) type 1 and 2A, Familial Hypocalciuric Hypercalcemia (FHH), and Hyperparathyroidism-Jaw Tumor Syndrome (HPT-JT). MEN 1 is characterized by a loss of function in the tumor suppressor gene, Menin, whereas MEN 2 is characterized by a gain of function mutation in the RET proto-oncogene. FHH is characterized by mutations that alter the calcium-sensing receptor in the kidney and parathyroid glands, resulting in mild hypercalcemia and elevated PTH levels. HPT-JT is characterized by hereditary predisposition to jaw tumors and benign and malignant tumors of the parathyroids. All four syndromes are autosomal dominant, with variable penetrance of degree of clinical hyperparathyroidism. Each of these disorders requires careful evaluation, diagnostic testing, genetic analysis, and potentially, surgical management.

A Portuguese kindred with autosomal dominant isolated primary hyperparathyroidism (HPT) that was associated with parathyroid adenomas and carcinomas was investigated with the aim of determining the chromosomal location of this gene, designated HPTPort. Leukocyte DNA from 9 affected and 16 unaffected members and 7 parathyroid tumors from 4 patients was used in comparative genomic hybridization (CGH), tumor loss of heterozygosity (LOH), and family linkage studies. The CGH studies revealed abnormalities of chromosomes 1 and 13, and the results of LOH studies were consistent with the involvements of tumor suppressor genes from these regions. Family segregation studies mapped HPTPort to chromosome 1q22-q31 by establishing linkage with eight loci (D1S254, D1S222, D1S202, D1S238, D1S428, D1S2877, D1S422, and D1S412) (peak two-point LOD scores = 3. 46-5.14 at 0% recombination), and defined the location of HPT Port to a 21 cM region flanked centromerically by D1S215 and telomerically by D1S306. Thus, HPTPort has been mapped to chromosome 1q22-q31, and a characterization of this gene will help to elucidate further the mechanisms that are involved in the development of parathyroid tumors.

The hyperparathyroidism-jaw tumor (HPT-JT) syndrome is an autosomal dominant disorder characterized by the occurrence of parathyroid tumors in association with ossifying fibromas of the maxilla and/or mandible. The gene responsible for HPT-JT, known as CDC73, was identified in 2002 and encodes a 531 amino acid protein known as parafibromin. Parafibromin is predominantly a nuclear protein that interacts directly with beta-catenin and also forms part of the RNA polymerase associated factor-1 complex (Paf1C) that regulates transcription. Heterozygous germline CDC73 mutations are detected in the majority of patients with HPT-JT, and the demonstration of loss of heterozygosity (LOH) at the CDC73 locus in tumors from affected individuals is consistent with a tumor suppressor role. Somatic CDC73 mutations are a frequent finding in nonfamilial (i.e., sporadic) parathyroid carcinomas and have also been reported in benign sporadic parathyroid tumors as well as sporadic renal and fibro-osseous jaw tumors. To date, 111 independent CDC73 mutations have been identified (68 germline; 38 somatic; 5 undefined), and these occur throughout the coding region and splice sites of the CDC73 gene, with the majority (>80%) predicting premature truncation of the parafibromin protein. These CDC73 mutations, together with their clinical and biological relevance, are reviewed.

INTRODUCTION: Cancer in the parathyroid gland is rare, but parathyroid cancer is occasionally seen in relation to genetic abnormalities. Due to a limited amount of evidence, the optimal handling of these cases is not clear. Furthermore, the presence of a malignant parathyroid tumor is rarely known at the time of the initial operation; therefore, re-operations are often necessary. The aim of this study was to present the case of a patient with a previously diagnosed jaw tumor and parathyroid carcinoma that presents as a recurrence of hyperparathyroid hypercalcemia.CASE PRESENTATION: A 41-year-old patient who was already diagnosed with a parathyroid carcinoma and a jaw tumor caused by a CDC73 mutation, presented with biochemical evidence of increasing parathyroid hormone (PTH) and calcium levels after a previous total parathyroidectomy. The patient's ionized calcium increased to 1.55 mmol/L and PTH increased to 16.0 pmol/L. A previous genetic analysis revealed a mutation in the CDC73 gene. There was no family history of hyperparathyroidism. We performed a sestamibi scintigraphy and an 11-C methionine (MET) positron emission tomography (PET) scan that showed a recurrence on the left side of the trachea. The patient underwent a third neck operation for the removal of a tumor on the left side of the trachea. The pathology report revealed that the tumor was a lymph node metastasis from the previous parathyroid carcinoma. The patient is currently enrolled in our follow-up regime. Hyperparathyroidism-jaw tumor (HPT-JT) syndrome is a rare autosomal dominant disorder characterized by a parathyroid adenoma or carcinoma, fibro-osseous lesions (ossifying fibroma) of the mandible and maxilla, and renal cysts and tumors. This autosomal dominant familial cancer syndrome has been reported with a variable and incomplete penetrance, and up to 10% of gene carriers do not show any clinical manifestations. Here we present a patient's case and discuss the literature related to this condition.CONCLUSIONS: The recurrence of hyperparathyroid hypercalcemia in HTP-JT syndrome after an initial total parathyroidectomy is a well-known condition necessitating careful management, an evaluation of any underlying genetic abnormality, and a family examination. A surgical treatment and surveillance of calcium and PTH measurements are necessary to prevent a recurrence.

Hyperparathyroidism-jaw tumor syndrome (HPT-JT) is a rare autosomal disease caused by inactivating germ-line mutations of HRPT2 gene, with subsequent loss of Parafibromin expression. It is characterized by familial HPT, ossifying jaw tumors, and other associated neoplasms.Clinical, histopathological, and genetic features of three large Italian unrelated HPT-JT kindred were assessed.Three different germ-line HRPT2 inactivating mutations were identified. Seventeen affected members and six healthy mutation carriers were found. HPT was diagnosed in virtually all affected patients, at a median age of 36.3 years (range 11-71). In all cases, a single parathyroid involvement was found at surgery, although a metachronous multiglandular involvement causing recurrence after selective parathyroidectomy occurred in 17.6% of cases, after a mean disease-free interval of 13.7 years (range 5-27). Parathyroid carcinoma, atypical parathyroid adenoma, and jaw tumor occurred in one case; uterine involvement in 61.5% of women; other associated neoplasms were thyroid carcinoma (two cases) and renal and colon carcinoma (one case). Immunohistochemistry confirmed the loss of Parafibromin as the distinctive feature of the disease both in parathyroid and uterine tumors.HPT-JT has a frequent single-gland parathyroid involvement and a relatively increased risk of parathyroid carcinoma. The penetrance of the disease is high but incomplete. Regardless of the denomination of the syndrome, jaw tumors occur rarely, while uterine involvement is frequently present. Selective parathyroidectomy may be an effective strategy, but a prolonged follow-up is required because of the risk of recurrences and malignancies. A systematic investigation is also required because of associated malignancies.

Primary hyperparthyrodism (PHPT) is a common endocrine disease. It results from an inappropriate parathyroid hormone (PTH) secretion relative to serum ionized calcium level. Clinical manifestation of severe PHPT include bone disease called osteitis fibrosa cystica which reflects an increase osteoclastic resorption and osteoblastic activity. This high bone turnover is responsible of the occurrence of osteoclastomas, also named "brown tumors" (1). Rarely, PHPT may occur in inherited forms with association to fibrous jaw tumor that are unrelated to hyperparathyroidism. In this uncommon disease: hyperparathyroidism-jaw tumor (HPT-JT) syndrome, parathyroid tumor is frequently malignant and usually associated with nonendocrine malignancies (2). We report a case of a HPT-JT syndrome to focus on the differential diagnosis with brown tumors.

Familial hyperparathyroid syndromes involving mutations of HRPT2 (also CDC73), a tumor suppressor, are important to identify because the relatively high incidence of parathyroid malignancy associated with such mutations warrants a specific surveillance strategy. However, there is a dearth of reports describing experience with surveillance and early detection informed by genetic insight into this disorder. Introduction: Familial isolated hyperparathyroidism (FIHP) is a rare cause of parathyroid (PT) tumors without other neoplasms or endocrinopathies. Germline mutations in CASR, MEN1, and rarely, HRPT2 have been identified in kindreds with FIHP. HRPT2 mutations may be enriched in FIHP families with PT carcinoma, underscoring the importance of identifying causative mutations. Materials and Methods: A 13-year-old boy, whose father had died of PT carcinoma, developed primary hyperparathyroidism. A left superior PT mass was identified by ultrasonography and removed surgically. Aggressive histological features of the boy's tumor included fibrous trabeculae, mitoses, and microscopic capsular infiltration. Two years later, under close biochemical surveillance, primary hyperparathyroidism recurred 5 months after documentation of normocalcemia and normal parathyroid status. Ultrasound and MRI identified a newly enlarged right superior PT gland but indicated no recurrent disease in the left neck. Histologic features typical of a benign adenoma were evident after surgical extirpation of the gland. Results: Leukocyte DNA analysis revealed a frameshift mutation in exon 2 of HRPT2. The initial tumor manifested the expected germline HRPT2 mutation, plus a distinct somatic frameshift mutation, consistent with the Knudson “two hit” concept of biallelic inactivation of a classic tumor suppressor gene. Genetic screening of the patient's 7 asymptomatic and previously normocalcemic siblings revealed three with the same germline HRPT2 mutation. One of the siblings newly identified as mutation-positive was noted to be hypercalcemic at the time of the genetic screening. He was found to have a PT adenoma with aggressive features. Two of the five children of another mutation-positive sibling also carry the same HRPT2 mutation. Conclusions: Despite the reported rarity of HRPT2 mutations in FIHP, a personal or family history of PT carcinoma in FIHP mandates serious consideration of germline HRPT2 mutation status. This information can be used in diagnostic and management considerations, leading to early detection and removal of potentially malignant parathyroid tumors.

Summary Background A subset of familial isolated primary hyperparathyroidism (FIHP) is a variant of hyperparathyroidism–jaw tumour syndrome (HPT-JT). Aim/patients and methods We investigated the involvement of the HRPT2, MEN1 and CASR genes in 11 provisional FIHP families and two HPT-JT families. Results Germline mutations of HRPT2 were found in two of the 11 FIHP families and one of the two HPT-JT families. One FIHP family with parathyroid carcinoma and atypical adenomas and another FIHP family with cystic parathyroid adenoma had novel frameshift mutations of 518–521del and 62–66del, respectively. In a patient with HPT-JT, a de novo germline mutation of 39delC was detected. Novel somatic HRPT2 mutations of 70–73del and 95–102del were found in two of five parathyroid tumours in a family with a 518–521del mutation. Biallelic inactivation of HRPT2 by a combination of germline and somatic mutation was confirmed in the parathyroid tumours. The finding that two families diagnosed with FIHP carried HRPT2 mutations suggests that they have occult HPT-JT. In the remaining 10 families, one family had a missense MEN1 mutation. No mutations of CASR were detected. Conclusion Our results confirm the need to test for HRPT2 in FIHP families, especially those with parathyroid carcinomas, atypical adenomas or adenomas with cystic change.

Hyperparathyroidism-jaw tumor syndrome (HPT-JT) is an important diagnosis because of the possible involvement of other family members and risk of malignant disease. We report clinical and genetic studies in a previously undocumented Australian family with HPT-JT. The proband and his sister presented with bilateral or recurrent mandibular radiolucencies diagnosed histopathologically as cemento-ossifying fibromas. Mutation screening of the recently identified disease gene HRPT2 was performed by direct sequencing in 3 affected members. This revealed a novel mutation in exon 1 of HRPT2 (nt 20AGGACG --> GGGAG), which is predicted to inactivate the parafibromin protein through protein truncation and premature termination of translation. The terminology used for the jaw lesions in this syndrome warrants review to become more consistent. Cemento-ossifying fibroma is the preferred term to better reflect the pathologies found in most individuals and families,and to emphasize the significance of the jaw lesions in the diagnosis of the syndrome.

We investigated the involvement of the HRPT2 gene by loss of heterozygosity analysis and direct sequencing in a kindred with hyperparathyroidism-jaw tumor syndrome (HPT-JT) and three kindreds with familial isolated primary hyperparathyroidism (FIHP). Seven patients with sporadic parathyroid cancers and 35 with parathyroid adenomas with no family history of primary hyperparathyroidism or HPT-JT were also studied. A germline heterozygous substitution G to A was found in the donor splice site of intron 1 in one of the three FIHP families. No mutations were identified in the HPT-JT kindred. A somatic HRPT2 mutation was found in four of seven patients with parathyroid cancers, two of which were unreported frameshift mutations (195insT and 195insA) in exon 2. Consistent with recent findings, two of seven patients with sporadic parathyroid cancer had germline mutations. Four adenomas showed loss of heterozygosity at HRPT2, whereas a somatic HRPT2 mutation was found in one. In conclusion, we provide additional evidence for a strong association between HRPT2 gene mutations and sporadic parathyroid cancer. The finding that two of the seven patients with sporadic parathyroid cancer carried an HRPT2 germline mutation suggests that they might have occult HPT-JT. Our results also confirm the need for testing HRPT2 gene in FIHP families.

Purpose: A reliable method for diagnosing parathyroid carcinoma has remained elusive over the years, resulting in its under-recognition and suboptimal therapy. Obtaining an accurate diagnosis has become an even more pressing matter with recent evidence that germline HRPT2 gene mutations are found in patients with apparently sporadic parathyroid carcinoma. There is a high prevalence of HRPT2 gene mutations and biallelic inactivation in parathyroid carcinoma. We hypothesize that loss of parafibromin, the protein product of the HRPT2 gene, would distinguish carcinoma from benign tissue. Experimental Design: We generated a novel antiparafibromin monoclonal antibody and performed immunostaining on 52 definite carcinoma specimens, 6 equivocal carcinoma specimens, 88 benign specimens, and 9 hyperparathyroidism-jaw tumor (HPT-JT) syndrome-related adenomas from patients with primary hyperparathyroidism from nine worldwide centers and one national database. Results: We report that the loss of parafibromin nuclear immunoreactivity has 96% sensitivity [95% confidence interval (CI), 85–99%] and 99% specificity (95% CI, 92–100%) in diagnosing definite carcinoma. Inter-observer agreement for evaluation of parafibromin loss was excellent, with unweighted kappa of 0.89 (95% CI, 0.79–0.98). Two equivocal carcinomas misclassified as adenomas were highlighted by parafibromin immunostaining. One of these tumors has since recurred, satisfying criteria for a definite carcinoma. Similarly, eight of nine HPT-JT syndrome-related adenomas showed absent nuclear immunoreactivity. Conclusions: Parafibromin is a promising molecular marker for diagnosing parathyroid carcinoma. The similar loss of parafibromin immunoreactivity in HPT-JT syndrome-related adenomas suggests that this is a pivotal step in parathyroid tumorigenesis.

Familial hyperparathyroidism is not uncommon in clinical endocrine practice. It encompasses a spectrum of disorders including multiple endocrine neoplasia types 1 (MEN1) and 2A, hyperparathyroidism-jaw tumour syndrome (HPT-JT), familial hypocalciuric hypercalcaemia (FHH), and familial isolated hyperparathyroidism (FIHP). Distinguishing among the five syndromes is often difficult but has profound implications for the management of patient and family. The availability of specific genetic testing for four of the syndromes has improved diagnostic accuracy and simplified family monitoring in many cases but its current cost and limited accessibility require rationalisation of its use. No gene has yet been associated exclusively with FIHP. FIHP phenotypes have been associated with mutant MEN1 and calcium-sensing receptor (CASR) genotypes and, very recently, with mutation in the newly identified HRPT2 gene. The relative proportions of these are not yet clear. We report results of MEN1, CASR, and HRPT2 genotyping of 22 unrelated subjects with FIHP phenotypes. We found 5 (23%) with MEN1 mutations, four (18%) with CASR mutations, and none with an HRPT2 mutation. All those with mutations had multiglandular hyperparathyroidism. Of the subjects with CASR mutations, none were of the typical FHH phenotype. These findings strongly favour a recommendation for MEN1 and CASR genotyping of patients with multiglandular FIHP, irrespective of urinary calcium excretion. However, it appears that HRPT2 genotyping should be reserved for cases in which other features of the HPT-JT phenotype have occurred in the kindred. Also apparent is the need for further investigation to identify additional genes associated with FIHP.

Background: Hyperparathyroidism is a common endocrinopathy characterised by the formation of parathyroid tumours. In this study, we determine the role of the recently identified gene, HRPT2 , in parathyroid tumorigenesis. Methods: Mutation analysis of HRPT2 was undertaken in 60 parathyroid tumours: five HPT-JT, three FIHP, three MEN 1, one MEN 2A, 25 sporadic adenomas, 17 hyperplastic glands, two lithium associated tumours, and four sporadic carcinomas. Loss of heterozygosity at 1q24-32 was performed on a subset of these tumours. Results: HRPT2 somatic mutations were detected in four of four sporadic parathyroid carcinoma samples, and germline mutations were found in five of five HPT-JT parathyroid tumours (two families) and two parathyroid tumours from one FIHP family. One HPT-JT tumour with germline mutation also harboured a somatic mutation. In total, seven novel and one previously reported mutation were identified. “Two-hits” (double mutations or one mutation and loss of heterozygosity at 1q24-32) affecting HRPT2 were found in two sporadic carcinomas, two HPT-JT-related and two FIHP related tumours. Conclusions: The results in this study support the role of HRPT2 as a tumour suppressor gene in sporadic parathyroid carcinoma, and provide further evidence for HRPT2 as the causative gene in HPT-JT, and a subset of FIHP. In light of the strong association between mutations of HRPT2 and sporadic parathyroid carcinoma demonstrated in this study, it is hypothesised that HRPT2 mutation is an early event that may lead to parathyroid malignancy and suggest intragenic mutation of HRPT2 as a marker of malignant potential in both familial and sporadic parathyroid tumours.

Background Hyperparathyroidism–jaw tumor (HPT-JT) syndrome is a rare autosomal dominant multiple tumor syndrome characterized by hyperparathyroidism due to single or multiple-gland parathyroid tumor(s). Since it was first described in 1990, the genetics underlying the syndrome have been elucidated and typical clinical presentations are becoming clarified as literature describing this rare entity amasses. Methods and Results A 22-year-old man presented with a 2-year history of fatigue, weight loss, nausea, and vomiting. Anemia workup indicated severe hypercalcemia. Investigations were consistent with a diagnosis of HPT-JT. The patient underwent a total 4-gland parathyroidectomy with single gland reimplantation. Conclusion HPT-JT is a complex syndrome with phenotypic manifestations that can seem physiologically and temporally unrelated. The risk of parathyroid carcinoma is elevated in patients with HPT-JT, necessitating rapid treatment and complete tumor resection to reduce the morbidity and mortality associated with intractable hypercalcemia due to local recurrence or metastatic disease. © 2012 Wiley Periodicals, Inc. Head Neck, 2012

Parathyroid carcinoma is a rare endocrine neoplasm, usually causing severe primary hyperparathyroidism, that frequently causes death from unmanageable hypercalcemia. At times, the diagnosis can be difficult. Currently, the pathological diagnosis of parathyroid carcinoma is restricted to lesions showing unequivocal growth into adjacent tissues or metastasis. Inactivating mutations of CDC73 gene have been identified in up to 70% of apparently sporadic parathyroid carcinomas and up to one-third of cases had germline mutations. Loss of parafibromin expression on immunohistochemistry has been found in the majority of parathyroid carcinomas. The presence of both CDC73 mutations and loss of parafibromin seems to predict a worse clinical outcome and a lower overall 5- and 10-year survival. The treatment of choice is the en bloc resection of the tumor, which should be performed in all patients with clinical suspicion of parathyroid cancer. The course of parathyroid carcinoma is variable and patients may have local recurrences or distant metastases.

Ossifying fibromas of the maxillofacial bones are an uncommon form of benign neoplasm usually treated by surgical excision. Up to 30% of patients with hyperparathyroidism-jaw tumor syndrome, a rare form of multiple endocrine neoplasia resulting from autosomal dominant inactivating mutation of the Hrpt2 tumor suppressor gene, initially present with ossifying fibromas. Coincident hypercalcemia because of the presence of parathyroid adenoma is common in these patients, of whom 15% may have or may develop parathyroid carcinoma. The authors present a case of severe postsurgical hypercalcemia after removal of a large maxillary ossifying fibroma in a patient with previously unrecognized hyperparathyroidism-jaw tumor AU3 syndrome.

Familial primary hyperparathyroidism is the main feature of 2 familial endocrine neoplasia syndromes: multiple endocrine neoplasia type 1 (MEN 1) and hyperparathyroidism-jaw tumor syndrome (HPT-JT). The latter is a recently described syndrome that has been associated with ossifying fibroma of the jaw and various types of renal lesions, including benign cysts, Wilms’ tumor, and hamartomas. To further illustrate the natural history of this syndrome, we describe a large, previously unreported Dutch kindred in which 13 affected members presented with either parathyroid adenoma or carcinoma; in 5 affected individuals, cystic kidney disease was found. Additionally, pancreatic adenocarcinoma, renal cortical adenoma, papillary renal cell carcinoma, testicular mixed germcell tumor with major seminoma component, and Hürthle cell thyroid adenoma were also identified. Linkage analysis of the family using MEN1-linked microsatellite markers and mutation analysis excluded the involvement of the MEN1 gene. Using markers from the HPT-JT region in 1q25–31, cosegregation with the disease was found, with a maximum logarithm of odds score of 2.41 obtained for 6 markers using the most conservative calculation. Meiotic telomeric recombination between D1S413 and D1S477 was identified in 3 affected individuals, and when combined with previous reports, delineated the HPT-JT region to 14 centimorgan. Combined comparative genomic hybridization and loss of heterozygosity data revealed complex genetic abnormalities in the tumors, suggesting different possible genetic mechanisms for the disease. In conclusion, we report a family with hyperparathyroidism linked to chromosome 1q, and exhibiting several types of renal and endocrine tumors that have not been previously described.