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Solid pseudopapillary neoplasms (SPNs) and pancreatic neuroendocrine tumors (PanNETs) are distinctive entities. However, due to overlapping morphologies, distinguishing them remains a diagnostic challenge. Our study investigates the utility of immunohistochemistry for nuclear lymphoid enhancer binding factor 1 (LEF1) and paired box gene 8 (PAX8) in differentiating these 2 entities. LEF1 and PAX8 immunohistochemistry were performed on fine-needle aspiration cell blocks and surgical resection specimens diagnosed as SPN or PanNET at our institution from January 2007 to August 2016. Eight SPN and 25 PanNET cell blocks and 17 SPN and 34 PanNET surgical resection specimens were examined. On cell blocks, positive staining for LEF1 had high frequency, sensitivity, and specificity for SPN (88%, 88%, and 88%) as did positive staining for PAX8 for PanNET (76%, 76%, and 75%). The findings on surgical resection specimens were consistent with those from cell blocks (LEF1+ in SPN: 100%, 100%, and 97%; PAX8+ in PanNET: 59%, 59%, and 100%). A combined LEF1+/PAX8- phenotype showed high sensitivity and specificity for SPN (cell block: 63% and 100%; surgical specimen: 100% and 98%) as did a LEF1-/PAX8+ phenotype for PanNET (cell block: 64% and 100%; surgical specimen: 59% and 100%). SPN and PanNET exhibit opposite immunophenotypic profiles with LEF1+/PAX8- in SPN and LEF1-/PAX8+ in PanNET. The combination of these 2 stains provides an effective means of distinguishing these 2 entities.

The presence of atypical endometrial cells in the Papanicolaou (Pap) test has been associated with an increased rate of endometrial malignancy, with reported rates ranging from 14% to 47%. However, most reported studies have focused on patients who were aged40 years. The purpose of the present study was to investigate the clinical significance of identifying atypical endometrial cells in Pap test samples in women aged40 years of age.A search of the cytology Pap test database was performed from 2000 to 2014 using the keywords "atypical endometrial cells" or "atypical glandular cells favor endometrial origin" in women aged40 years. The available ThinPrep slides were reviewed. The patients' clinical presentation, follow-up endometrial biopsy findings, treatment, and clinical follow-up data were recorded. Endometrial carcinoma tissue sections were screened for Lynch syndrome.The database search yielded 63 study cases. Of these 63 patients, 52 had subsequently undergone endometrial biopsy. Of the 52 patients with follow-up biopsy findings available, 9 (17.3%) had premalignant (5 with atypical hyperplasia) or malignant (4 with endometrioid adenocarcinoma) lesions. In addition, 16 patients (30.8%) had other endometrial pathologic features. The 9 patients with premalignant or malignant endometrial lesions (8 white, 1 black) were overweight or obese; 3 of the patients did not have any clinical symptoms. All 4 patients with endometrioid adenocarcinoma had negative Lynch syndrome screening findings.Our results suggest that it is important to recognize the presence of atypical endometrial cells in the Pap tests from young patients, given its association with the finding of premalignant and malignant pathologic features in subsequent endometrial biopsies.

BACKGROUND Primary salivary gland-type tumors of the tracheobronchial tree are rare; their cytologic features have been seldom reported. We aim to describe the clinical and cytomorphologic features of tracheobronchial salivary gland-type tumors diagnosed by transbronchial fine needle aspiration (TBNA) at our institution, and correlate the findings with a corresponding surgical specimen. METHODS We searched our laboratory information system to identify patients with a primary salivary gland-type neoplasm of the tracheobronchial tree diagnosed by TBNA and with a corresponding surgical pathology specimen, over 10 years. RESULTS The study cohort consisted of 11 patients (7F/4M; mean age 58 years, range 41-78). Presenting symptoms included hemoptysis (4), cough (3), dyspnea (1), stridor (1), and shoulder pain (1). Most had a tracheal mass (5), while 3 had mainstem bronchi masses and 3 had lung masses. Radiographically, the masses were lobulated, rounded, or polypoid in six patients. All underwent TBNA with a 21- or 22-gauge needle and endobronchial biopsy. The most frequent diagnosis was adenoid cystic carcinoma (4/11, 36%), followed by mucoepidermoid carcinoma (3/11, 27%), epithelial-myoepithelial carcinoma (2/11, 18%), oncocytoma (1/11, 9%), and hyalinizing clear cell carcinoma, salivary gland type (1/11, 9%). The surgical pathology specimens confirmed the diagnosis in all cases. CONCLUSIONS To our knowledge, this is one of the largest cytomorphologic studies of primary salivary gland tumors of the tracheobronchial tree in the literature. Salivary gland tumors of the tracheobronchial tree are rare, and recognizing cytomorphologic changes that occur in salivary gland-type tumors is important for establishing a definitive diagnosis.

Context.—Recent advances in comprehensive genomic profiling by next-generation sequencing have uncovered the genomic alterations at the molecular level for many types of tumors; as such, numerous small specific molecules that target these alterations have been developed and widely used in the management of these cancers.Objective.—To provide a concise molecular genomic update in solid, bone and soft tissue tumors, hematopoietic as well as lymphoid malignancies; discuss its clinical applications; and familiarize practicing pathologists with the emerging cancer biomarkers and their diagnostic utilities.Data Sources.—This review is based on the National Comprehensive Cancer Network guidelines and peer-reviewed English literature.Conclusions.—Tumor-specific biomarkers and molecular/genomic alterations, including pan-cancer markers, have been significantly expanded in the past decade thanks to large-scale high-throughput technologies and will continue to emerge in the future. These biomarkers can be of great value in diagnosis, prognosis, and/or targeted therapy/treatment. Familiarization with these emerging and ever-changing tumor biomarkers will undoubtedly aid pathologists in making accurate and state-of-the-art diagnoses and enable them to be more actively involved in the care of cancer patients.

Background Several previous studies have described broad histologic classifications of peri-prosthetic reactions that likely reflect the underlying mechanism of arthroplasty failure; however, a consensus has not yet been reached about the relative importance of individual observations. Question/Purpose The purpose of this study was to evaluate the inter-examiner repeatability of commonly used histopathologic grading methods, and to determine the utility of assigning a more simple, global categorization in patients undergoing revision THA surgery of implants with a variety of bearing combinations. Methods Between March 2013 and February 2020, a total of 2131 patients underwent revision hip arthroplasty surgery at a one center, of which 12% (248 of 2131) of patients were enrolled. Two pathologists independently reviewed microscope slides of periprosthetic tissue from these patients, of which 425 slides (229 hips, 222 subjects) were reviewed by both pathologists. Separate slides were used for a priori training of the pathologists. Slides were evaluated with the Campbell Aseptic Lymphocyte-dominant Vasculitis-Associated Lesion (ALVAL) score, the Oxford ALVAL score as modified by Grammatopolous, the Fujishiro and Natu scores, and a proposed simplified pattern classification, similar to that of Krenn et al., that incorporates individual factors of these existing scoring methods and was previously shown to correspond to Magnetic Resonance Imaging findings. Inter-rater agreement was assessed using Gwet’s AC1 and AC2 coefficients and correspondence analysis was used to examine associations between individual factors of prior scoring methods with the proposed major pattern. Results Almost perfect inter-rater repeatability (Gwet’s AC2 > 0.8) was found for 71% (15/21) of the individual factors, and substantial interrater agreement was found for the proposed major overall pattern (Gwet’s AC1: 0.80, 95%CI: 0.72–0.85). Correspondence analysis was able to explain 89–91% of data variability and was able to identify individual features not commonly associated with a major pattern, but discriminatory of the major pattern, such as “Lymph Cuff Thickness 0.25–0.5″ with ALVAL. Conclusion In contrast to prior examinations, excellent interrater agreement was found that may be attributable to a priori training of raters with a test set of slides or difficulty of interpreting grading criteria. The proposed simplified major pattern classification may facilitate evaluation of histopathologic tissue samples.

Bone-forming tumors are defined by neoplastic cells that differentiate along the lines of osteoblasts that deposit neoplastic bone. The morphology and biological spectrum of bone-forming tumors is broad, and their accurate diagnosis requires the careful correlation of their clinical, morphologic, and radiologic characteristics. Immunohistochemical and molecular analyses have an important role in select instances. At present, the identification of neoplastic bone largely depends on histologic analysis, which can be subjective. The major types of osteosarcoma are defined according to their morphology, origin within or on the surface of the bone, and their histologic grade.

Introduction Polyomavirus cytopathic effect (BK-CPE) is classified as “negative for high-grade urothelial carcinoma” (NHGUC) in the Paris System for Reporting Urinary Cytology. However, polyomaviruses have been historically associated with tumor development and have been recently reported as an independent risk factor for renourinary carcinoma in transplant patients. The aim of the present study was to investigate the relationship between polyomavirus infection in the urinary tract and the subsequent risk of developing high-grade urothelial carcinoma (HGUC) in the general population. Materials and methods: A retrospective case-control study was conducted to assess BK-CPE in all urinary cytology examinations performed from 2009 to 2011 for cases with an interpretation of NHGUC, NHGUC with BK, atypical urothelial cells (AUCs), or AUCs with BK. The endpoint of the present study was a diagnosis of HGUC on either bladder biopsy or urine cytology for those patients with subsequent follow-up data. Results A total of 252 cases with a urinary cytology interpretation of NHGUC, 234 with NHGUC + BK, 255 with AUCs, and 64 with AUCs + BK were identified. The surgical and cytological follow-up data showed that the overall risk of the development of HGUC for those with NHGUC, NHGUC + BK, AUCs, and AUCs + BK was 6.0%, 6.8%, 23.5%, and 12.5%, respectively. No statistically significant differences were found between the patients with NHGUC and those with NHGUC + BK. A statistically significant difference was found for patients with AUCs compared with patients with NHGUC + BK and those with AUCs + BK (P Conclusions The presence of BK-CPE in urine cytology samples does not increase the overall risk of the development of HGUC. Our results support the recommendation from the Paris System for Reporting Urinary Cytology to place urine samples with BK-CPE in the NHGUC category.

Polyomavirus-associated nephropathy (PVAN) is one of the most common disease affecting transplant patients, mainly caused by BK polyomavirus (BKV) and with5% of the cases caused by JC polyomavirus (JCV). Screening and early intervention, including appropriate reduction in immunosuppressive therapy, are critical to reduce allograft loss. The presence of decoy cells in the urine is a characteristic cytopathic effect of polyomavirus. The goal of this study was to investigate the significance of decoy cells in urine cytology in transplant patients, comparing with the plasma viral replication level detected by the real-time quantitative BK virus polymerase chain reaction test (Qt-BK PCR).A cohort of post-transplantation patients with serum BKV level monitored by Qt-BK PCR from 2008 to 2013 was studied. Among them, 35 patients had both urine cytology (UC) analysis and Qt-BK PCR performed. The clinical presentation along with the available UC slides were retrieved and reviewed.Compared with Qt-BK PCR, the sensitivity, specificity, positive predictive value, and negative predictive value of urine cytology analyzed within one week apart were 92%, 71%, 85%, and 83%, respectively. The accuracy of the UC was 84%. More interestingly, UC played a key role in identifying a case of JCV associated PVAN whereas Qt-BK PCR from both urine and plasma failed to detect this virus.Our data suggests that urine cytology is a sensitive surveillance test for early detection of polyomavirus in transplant patients, and it is particularly useful to screen for rare JC polyomavirus.

Total joint arthroplasty is one of the most successful of all operations, but arthroplasty failures do occur. By evaluating the retrieved devices and periprosthetic tissues, pathologists can often recognize clues about the mechanism of arthroplasty failure, information that can be of value to treating physicians, manufacturers and regulatory bodies. In this review, we provide an overview of the history of joint replacement implant development, describe the most common mechanisms of arthroplasty failure, and illustrate the types of damage that can be recognized during gross evaluation of retrieved devices. We emphasize the histologic findings in periprosthetic tissues, especially features typical of infection or other adverse local tissue reactions. We also summarize the histology of bone grafts and graft substitute materials in biopsy and resection specimens, which can help explain unexpected histologic findings at sites of prior reconstructive orthopaedic surgery, and can contribute to the development of new materials.

Context.— Given the increasing demand for molecular testing of non–small cell lung carcinoma specimens to guide therapeutic decision-making and the trend toward minimally invasive techniques for obtaining diagnostic tissue, cytopathology laboratories must devise strategies to maximize DNA yield for necessary molecular testing. Objective.— To describe our experience at Cleveland Clinic with epidermal growth factor receptor (EGFR) mutation testing by next-generation sequencing and anaplastic lymphoma kinase (ALK) gene rearrangement testing by fluorescence in situ hybridization of non–small cell lung carcinomas diagnosed by cytology, with an emphasis on specimens obtained by endobronchial ultrasound–guided transbronchial fine-needle aspiration. Data Sources.— Data sources include a review of the current literature, including published articles from our institution. Conclusions.— At our institution, liquid-based cytology specimens are the primary resource used for molecular testing of non–small cell lung carcinomas; in most instances, adequate DNA can be extracted from the residual cell pellet for next-generation sequencing, and ThinPrep slides can be used reliably for fluorescence in situ hybridization testing for ALK gene rearrangements. In occasional cases where the cell pellet material is not adequate for molecular testing, cell blocks and/or surgical pathology specimens are secondary options. The cytopathologist's role in specimen handling and triage is essential to ensure that molecular testing can be carried out successfully.

Angiomyolipoma (AML) arises primarily from the kidney but may grow into the retroperitoneal space mimicking a primary retroperitoneal tumor. Fine needle aspiration (FNA) and core needle biopsy of AML, particularly the fat-predominant variant, may be difficult to distinguish from retroperitoneal well-differentiated liposarcoma (WDLS) or lipoma. Commonly used immunomarkers, MDM2 and p16, have proven useful in diagnosing WDLS and dedifferentiated liposarcoma (DDLS), while HMB45 and Melan-A are melanocyte-related markers characteristically expressed in AML. In this study, we investigated the utility of MDM2 and p16 along with HMB45 and Melan-A immunohistochemical analysis in distinguishing AML from WDL/DDLS or lipoma. Immunohistochemically, AMLs demonstrated focal MDM2 expression (40% of cases) and focal/diffuse expression of p16 (60%). AMLs marked focally or diffusely with HMB45 (76% of cases) and Melan-A (96%). These latter two immunomarkers were not expressed in any of the WDLS/DDLSs or lipomas tested. WDLS/DDLSs showed focal/diffuse expression of MDM2 (91% of cases) and p16 (97%). While focal expression of MDM2 and p16 was observed in 14% and 67% of lipomas, respectively, no lipoma exhibited diffuse MDM2 positivity. In our hands, MDM2 expression by itself cannot exclude the diagnosis of AML or lipoma, and p16 alone is not helpful in separating AML and conventional lipoma from WDLS/DDLS. However, along with morphology, an immunohistochemical battery including HMB45, Melan-A, MDM2 and p16 are useful in distinguishing AML from WDLS/DDLS or lipoma. For equivocal cases, fluorescence in situ hybridization for MDM2 should be performed.

Cartilaginous neoplasms of soft tissue and synovium are relatively uncommon. The vast majority is benign and the neoplastic matrix is usually hyaline in type. The heterogeneity in their histologic features, especially the degree of cellularity and cytological atypia may pose challenges in diagnosis. Immunohistochemistry and molecular analyses are helpful in only specific circumstances stressing the importance of accurate histologic interpretation.

β-catenin immunohistochemical stain can be useful in the diagnosis of many tumors including desmoid-type fibromatosis (DTF). Lymphoid enhancer-factor 1 (LEF1), a recently emerged marker, is part of the Wnt pathway with β-catenin but has not been studied in DTF. We performed LEF1 and β-catenin immunohistochemistry in DTF (n=26), superficial fibromatosis (n=19), sclerosing mesenteritis (n=12), gastrointestinal stromal tumor (n=17), and cutaneous scar (n=14) using tissue microarray and whole sections. The staining intensity was scored as strong (visible at ×2 objective, value of 3), moderate (visible at ×4, value of 2), weak (visible at ×10, value of 1), and negative (not visible at ×10, value of 0). The percentage of positive nuclei was recorded in 10% increment. Histologic scores were generated by multiplying numerical value of intensity and percentage of positive nuclei. A score of at least 10 was defined as positive. Eighteen of the 25 DTF were positive for LEF1 while 12 of 25 were positive for β-catenin (1 excluded due to loss of tissue). Gastrointestinal stromal tumor cases were negative for both markers. All superficial fibromatoses were negative except 2 cases with weak positivity for LEF1 but not β-catenin. Only 2 case of sclerosing mesenteritis were weakly positive for LEF1 but negative for β-catenin. Ten of 14 scars were positive for LEF1 but only 1 of them was weakly positive for β-catenin. In conclusion, this study demonstrated that LEF1 may be a useful marker in the differential diagnosis of DTF in certain contexts. However, caution should be exercised since LEF1 positivity can also be seen in scars.

The endocrine system is an embryological diverse system consisted of a variety of glands, such as pituitary, parathyroid, thyroid, adrenal, endocrine pancreas, and the diffuse neuroendocrine system. Endocrine tumor can be presented as a sporadic event, or as part of an inherited tumor syndrome. During the past century, inherited tumor syndromes have emerged as an important group of diseases. With the growing knowledge of each inherited tumor syndrome in the molecular genetic level, many changes in clinical management have occurred. This review focuses on the endocrine tumors involving the pituitary, parathyroid, thyroid, adrenal, and endocrine pancreas, in the setting of inherited tumor syndromes. We discuss the specific clinical, molecular genetic, and pathologic features of endocrine tumor in each gland and their associated inherited tumor syndromes. By understanding the pathogenesis of inherited endocrine tumor syndromes and recognizing the unique features of pathologic findings, pathologists bear the responsibility to provide the clinicians the guidelines in terms of screening and treatment of inherited tumor syndromes.

Solid organ transplant–associated graft-versus-host disease is an infrequent and potentially lethal complication. The incidence of this complication varies according to the type of organ transplant with higher rates associated with liver and small bowel transplants. The clinical presentation typically includes fever and skin rash, and most cases quickly advance to become a multisystem disease affecting the bone marrow and other nontransplanted solid organs. The diagnosis is based on the clinical symptoms, pathologic changes in biopsied tissues, and systemic lymphoid chimerism. The mortality of this disease can exceed 75% after liver transplant and most patients die from infections or hemorrhage due to bone marrow failure. There is no standard treatment strategy for this complication, and the management mainly consists of both prophylaxis and immediate treatment without delay. This short review summarizes the current pathogenesis, diagnosis, and treatment of this entity.

Lesions that contain abundant benign myoepithelial cells, including pleomorphic adenomas of salivary gland origin, may present a diagnostic challenge in fine-needle aspiration (FNA) specimens. Benign metastasizing pleomorphic adenoma is a rare neoplasm, in which the benign appearing pleomorphic adenoma, without any histological evidence of malignancy, metastasizes to distant sites including lung. In the absence of clinical history of a pre-existing myoepithelial neoplasm, the presence of myoepithelial cells in the lung or any other organs besides salivary glands may create diagnostic difficulty. Here we present the cytologic findings of such a metastatic tumor found in the lung FNA and pleural fluid specimens from a 64-year-old woman, with a history of local recurrent salivary gland pleomorphic adenomas, who presented with multiple bilateral pulmonary nodules and pleural effusion. The diagnosis of benign metastasizing pleomorphic adenoma was made based on clinical information and cytomorphology, and confirmed by immunocytochemistry.

Pseudomyogenic hemangioendothelioma (PMH) is a well-recognized neoplasm that usually arises in the soft tissue; concurrent bone involvement occurs in 24% of cases. PMH of bone without soft tissue involvement is rare. We describe the clinicopathologic findings of 10 such cases, the largest series reported to date. The study included 9 male and 1 female patient; their ages ranged from 12 to 74 years (mean 36.7 y). All patients had multiple tumors with a distinct regional distribution: 45% restricted to the lower extremity; 25% to the spine and pelvis; and 15% to the upper extremity. On imaging studies the tumors were well circumscribed and lytic. The neoplasms were composed of spindled cells arranged in intersecting fascicles with scattered epithelioid cells; epithelioid cells predominated in 3 cases. The neoplastic cells contained abundant densely eosinophilic cytoplasm and vesicular nuclei. There was limited cytologic atypia and necrosis, few mitoses (0 to 2/10 high-power fields), and inconspicuous stroma. Unique findings included abundant intratumoral reactive woven bone and hemorrhage with numerous osteoclast-like giant cells. Immunohistochemically, most tumors were positive for keratin, ERG, and CD31; CD34 was negative. The balanced t(7:19)(q22;13) translocation was documented in 3 cases. Follow-up is limited, but no patient developed documented visceral dissemination, and all have stable or progressive osseous disease. PMH exclusively involving bone is rare. It is multicentric, often involves the lower extremity, and has unusual morphology. The differential diagnosis includes epithelioid vascular neoplasms, giant cell tumor, bone forming neoplasms, and metastatic carcinoma. Because of its rarity, unusual presentation, and morphology, accurate diagnosis can be challenging.

We report a unique case of an extramammary mammary-type myofibroblastoma of the perianal region. The patient was a 40-year old female with no significant past history, who presented with a right side painless perianal mass. Gross examination of the excised mass showed a well-circumscribed, apparently encapsulated, nodular mass weighing 30 g and measuring 5 cm. in the greatest dimension. The cut surface showed solid, yellow homogenous tissue. Microscopically, the neoplasm was composed of bland spindled cells generally arranged into short fascicles with abundant myxoid stroma. The cells stained strongly for desmin and CD34. To our knowledge, a review of the literature discloses only ten cases of extramammary, mammary-type myofibroblastoma.

Dedifferentiated chondrosarcoma is a primary bone tumor characterized by the presence of both low-grade cartilaginous and high-grade malignant noncartilaginous components. The high-grade noncartilaginous component is typically a pleomorphic fibroblastic spindle cell sarcoma. Dedifferentiation into a malignant epithelial component is extremely rare. In this report, we present a 74-year-old woman who developed a metastatic squamous cell carcinoma in the right inguinal area 1 year after wide resection of her right proximal femur for a dedifferentiated chondrosarcoma. The dedifferentiated component was composed of poorly differentiated epithelioid cells with foci of squamous cell carcinoma. Mutational analysis was performed, and the isocitrate dehydrogenase 1 R132C mutation was detected in the low-grade chondrosarcoma, dedifferentiated chondrosarcoma as well as the metastatic squamous cell carcinoma. And this mutation was not detected in patient's normal tissue. Our study supports the theory that both the chondrosarcoma cells and dedifferentiated epithelioid tumor cells arose from the same clonal origin.

Serous papillary carcinomas (SPCs) share a similar morphology regardless of whether they originate from the ovary or the uterus. Identification of the site of origin of the tumor can be a challenging and a diagnostic dilemma, particularly, in the setting of a pelvic mass or peritoneal carcinomatosis. Recognition of the site of origin influences the staging, management, and prognosis of these malignancies. The purpose of this study is to identify a panel of markers to distinguish the ovarian serous papillary carcinomas (OSPC) from the uterine serous papillary carcinomas (USPC). Formalin-fixed, paraffin-embedded archival tissue from 46 cases of SPCs (33 uterine and 13 ovarian) were stained using antibodies for estrogen receptor (ER), WT1, insulin-like growth factor-II mRNA-binding protein 3 (IMP3), p53, and p16. The OSPC expressed ER (92%), WT1 (100%), IMP3 (92%), p53 (92%), and p16 (92%). The USPCs expressed ER (30%), WT1 (64%), IMP3 (85%), p53 (64%), and p16 (76%). Only ER expression was significantly higher in OSPC compared with USPCs (P

Distinguishing chondrosarcoma from chondroblastic osteosarcoma can be difficult and highly subjective, especially on a small biopsy specimen. This distinction is critical in determining the most accurate prognosis and appropriate treatment modality, as adjuvant chemotherapy with surgery is standard treatment for osteosarcoma, whereas chondrosarcoma is generally treated by surgical excision alone. Cartilaginous neoplasms have recently been shown to frequently (56%) harbor gene mutations in the metabolic enzymes isocitrate dehydrogenase 1 (IDH1) and IDH2 (IDH1>IDH2), whereas other mesenchymal tumors lack these genetic aberrations. We investigated whether the presence of IDH1/2 mutations can be used to distinguish chondrosarcoma from chondroblastic osteosarcoma. Tumors including 25 predominantly high-grade chondrosarcomas and 65 osteosarcomas (44 chondroblastic osteosarcomas and 21 mixed osteosarcomas with a chondroblastic component) were evaluated, and a total of 59 cases (66%) were suitable for genotyping. Mutational analysis was performed using a multiplexed polymerase chain reaction genotyping platform to query for hotspot mutations in the genes IDH1 at codon R132. IDH1-negative cases underwent Sanger sequencing of IDH2 exon 4. No osteosarcomas (0/36) and 61% of chondrosarcomas (14/23) harbored a somatic mutation in IDH1/2, with the majority (86%) of mutations found in the IDH1 gene. IDH1/2 mutation analysis appears to be a promising biomarker for the distinction of chondrosarcoma from chondroblastic osteosarcoma. A positive result strongly favors the diagnosis of chondrosarcoma over chondroblastic osteosarcoma. The presence of IDH1/2 mutations can also help confirm the diagnosis of dedifferentiated chondrosarcoma when the tumor displays osteosarcomatous differentiation.

Systemic lymph node metastasis is a rare event in malignant mesothelioma. It is even more exceptional when systemic lymph node metastasis is the initial clinical presentation. Review of literature discloses only four cases in which metastatic lymphadenopathy was the only symptom of malignant mesothelioma. We, herewith, report three cases where the initial diagnosis of malignant mesothelioma was made by biopsy of enlarged lymph nodes, which were the only clinical presentation. Immunohistochemistry played a pivotal role in elucidating the mesothelial origin of their unusual systemic lymph node metastasis.