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Phosphaturic mesenchymal tumors are rare, usually benign neoplasms that occur in the soft tissue or bone and are the cause of nearly all cases of tumor-induced osteomalacia. Tumor-induced osteomalacia due to phosphaturic mesenchymal tumor is a challenging diagnosis to make-patients present with variable clinical and radiologic findings and the culprit neoplasm is often small and can occur anywhere head to toe. We present two cases of phosphaturic mesenchymal tumor in the scapular body and plantar foot. In both cases, the patient endured years of debilitating symptoms before a tissue diagnosis was eventually reached. Descriptions of clinical presentation, laboratory workup, surgical resection, and imaging characteristics, with a focus on CT, MRI, and functional imaging, are provided to assist with the diagnosis and management of this rare entity. A brief review of current literature and discussion of the differential diagnoses of phosphaturic mesenchymal tumor is also provided., (© 2023. The Author(s), under exclusive licence to International Skeletal Society (ISS).)

Tumor-induced osteomalacia (TIO) is rare paraneoplastic syndrome of hypophosphatemic osteomalacia, caused by phosphaturic factors secreted by small mesenchymal origin tumors with distinct pathological features, called 'phosphaturic mesenchymal tumors'. FGF23 is the most well-characterized of the phosphaturic factors. Tumors are often small and located anywhere in the body from head to toe, which makes the localisation challenging. Functional imaging by somatostatin receptor-based PET imaging is the first line investigation, which should be followed with CT or MRI based anatomical imaging. Once localised, complete surgical excision is the treatment of choice, which brings dramatic resolution of symptoms. Medical management in the form of phosphate and active vitamin D supplements is given as a bridge to surgical management or in inoperable/non-localised patients. This review provides an overview of the epidemiology, pathophysiology, pathology, clinical features, diagnosis, and treatment of TIO, including the recent advances and directions for future research in this field., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Oncogenic osteomalacia (OO) is an uncommon paraneoplastic syndrome occurring due to the presence of a tumour that oversecretes fibroblast growth factor-23, which impairs renal phosphate handling. In most cases, the tumour is a morphologically distinct entity called 'phosphaturic mesenchymal tumour' (PMT). Spinal tumours causing OO are exceedingly rare. A 55-year-old man presented with multiple bone pain and proximal muscle weakness in the lower limbs. The constellation of biochemical findings (hypophosphataemia, normocalcaemia, increased alkaline phosphatase, low-normal serum vitamin D and hyperphosphaturia) with radiographical rarefaction of the skeleton and pseudofractures led us to consider OO as a possibility. Functional imaging ( 68 Ga DOTA-NOC positron emission tomography/CT scan) localised the tumour to the D2 vertebra. Complete surgical resection led to resolution of symptoms, improved ambulatory status, normalisation of biochemical parameters and healing of pseudofractures. PMT should be considered in the differential diagnosis of hypophosphataemic osteomalacia with hyperphosphaturia. Tumour localisation with functional imaging and complete surgical resection produces satisfactory outcome., Competing Interests: Competing interests: None declared., (© BMJ Publishing Group Limited 2020. No commercial re-use. See rights and permissions. Published by BMJ.)

Tumor-induced osteomalacia (TIO) is a rare paraneoplastic syndrome of certain mesenchymal tumors which secrete fibroblast growth factor-23 (FGF-23) responsible for causing features of hypophosphatemia and osteomalacia in these patients. Most of them involve the appendicular skeleton and occasionally the craniofacial regions. Involvement of spine is exceedingly rare. Through this paper, the authors present a rare case of a 71-year-old male with TIO due to a lesion in the cervical spine (right C2 lamina) which was proven to be a phosphaturic mesenchymal tumor-mixed connective tissue type on histopathology. This is the fifth reported case of TIO localized to the cervical spine. The patient underwent a hemilaminectomy and gross total resection of the tumor following which he made a gradual but steady recovery and does not have any recurrence 24 months after surgery. The authors not only provide a comprehensive literature review of all 18 spinal cases reported till date but also discuss the management of these patients in light of the published literature., Competing Interests: None

Tumor-induced osteomalacia causing by phosphaturic mesenchymal tumor of the foot is exceedingly rare, thus may bring great challenges to the timely and proper diagnosis and treatment of clinicians. The only definitive management is removal of the phosphaturic mesenchymal tumor completely. The objective of this article is to report 2 unusual cases with tumor-induced osteomalacia causing by phosphaturic mesenchymal tumor of the foot.We describe 2 patients with phosphaturic mesenchymal tumor involving the foot who were successfully treated with tumor resection. On presentation to our institution, the patients both had signs of severe osteomalacia, and the patients' most outstanding complaints were diffuse bone pain, general weakness, and disabled walking. A 53-year-old female underwent surgical excision of pathogenic tumor on the sole of left foot. A 62-year-old female underwent complete excision of pathogenic tumor of right plantar. The patients showed appropriate destruction of the tumor, adequate pain relief, and the elevated blood phosphorus levels compared with the previous status.Surgical resection is the most effective treatment option for patients with tumor-induced osteomalacia who can undergo appropriate surgical treatment. This represents a safe and reasonable approach to sustainably relieve pain and other symptoms with tumor-induced osteomalacia in the foot.

Tumor-induced osteomalacia (TIO) is regarded as a rare paraneoplastic syndrome generally caused by phosphaturic mesenchymal tumors (PMTs). As far as we know, only 18 spinal PMTs have been described in the world's English literature. The purpose of this study is to increase familiarity with its clinical features, diagnosis, and treatment of spinal PMTs. A 34-year-old woman presented with bone pain for more than 3 years and was found to have decreased serum phosphorus, elevated serum alkaline phosphatase. A full body 68 Ga-DOTA-TATE PET/CT revealed increased uptake at the left posterior L5 neural arch. Then the tumor was totally resection and the histopathology revealed a PMT. Postoperatively, the patient's symptoms were relieved and experienced no recurrence during the 3-year follow-up. Generally, the preoperative diagnosis and location of spinal PMT still remains challenging. We also retrospectively analyzed 18 cases of patients with spinal PMTs published in English. Clinical symptoms, laboratory findings, treatment and outcome were retrospectively analyzed. Spinal PMTs are extraordinary and it is challengeable in locating tumors. Besides surgical resection, the treatment also included radiation, monoclonal antibodies or medical therapy. However, the optimal treatment remains controversial. Therefore, we should exert all our energies on the exploration of etiology and adjuvant therapy for this disease., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Tumor induced osteomalacia (TIO) is a paraneoplastic syndrome which is mostly caused by a phosphaturic mesenchymal tumour mixed connective tissue variant (PMTMCT). These tumours do not have any specific site predilection but their presence in cranial compartment is very rare. Two cases of TIO secondary to phosphaturic mesenchymal tumour at the skull base are described ahead, one of which was in the posterior fossa and the other in middle cranial fossa. Early diagnosis and complete excision of PMT is essential in preventing morbidity secondary to osteomalacia. This case report stands distinct in highlighting a rare site of a phosphaturic mesenchymal tumour and the need to keep a high index of suspicion in cases of TIO especially wherein localization of the tumour is unsuccessful., (© Journal of the Association of Physicians of India 2011.)

We report a case of tumor-induced osteomalacia (TIO) caused by a massive phosphaturic mesenchymal tumor (PMT) of the acetabulum. A 68-year-old woman presented with progressive bone pain of the rib cage, and polyarthralgia and back pain for 3 years. She was diagnosed with hypophosphatemic osteomalacia because laboratory testing was remarkable for low serum phosphorus and a low level of 1,25(OH)2 vitamin D. Three years later, her hip radiograph revealed an osteolytic lesion of the acetabulum. Magnetic resonance imaging of the acetabulum showed a massive lesion. Laboratory data showed hypophosphatemia and an elevated serum level of fibroblast growth factor 23 (FGF-23). Samples obtained with open biopsy showed a low-grade spindle cell neoplasm with FGF-23 positivity, identified by using immunohistochemical staining, confirming the diagnosis of a PMT mixed connective tissue variant. Curettage of the tumor was performed, and the defects were filled with bone allografts. The hip joint was reconstructed with total hip arthroplasty using a Muller support ring. To our knowledge, this report represents the first documented case of massive PMT of the acetabulum causing TIO.

Introduction: Osteomalacia is associated with diffuse pain and multiple fractures and therefore, diagnosis and treatment of this condition are necessary. Clinicians should be aware of an uncommon mechanism of osteomalacia where hypophosphataemia is secondary to renal phosphaturia because of the production by a mesenchymal phosphaturic tumor of FGF-23. This tumor should be localized and removed to cure this tumor-induced osteomalacia., Observation: A 70-year-old female patient was admitted to explore diffuse pain caused by multiple fractures secondary to osteomalacia. Despite vitamin D supplementation, she remained profoundly hypophosphoremic with major renal phosphaturia. A tumor-induced mechanism was suspected because of high level of FGF-23. It took more than three years of investigation to spot the causal phosphaturic mesenchymal tumor despite annual repetition of indium-labelled scintigraphy and PET-scan. The resection of the tumor, located between two phalanges of the right foot, cured the patient with sustained normal rate of serum level of phosphorus after two years., Conclusion: Tumor-induced osteomalacia is a diagnostic challenge because the localization of the tumor may be a long process. Patients should be monitored clinically and imaging studies repeated until a diagnosis is made and the causal tumor removed., (Copyright © 2016 Société Nationale Française de Médecine Interne (SNFMI). Published by Elsevier SAS. All rights reserved.)

Phosphaturic mesenchymal tumor (PMT) is a rare neoplasm; however, it is the most common cause of tumor-induced osteomalacia (TIO), a paraneoplastic syndrome characterized by renal phosphate wasting and hypophosphatemia. A subset of PMTs harbours an FGFR1 translocation although this alteration has not been demonstrated in PMT involving a head and neck site. We present a series of five PMTs involving the head and neck and demonstrate the diagnostic utility of fluorescence in situ hybridization (FISH) for detecting FGFR1 translocations. Patients' age and sex, tumor location, original diagnosis, the duration of symptoms, the presence of TIO, biochemical results, and medical management were reviewed. The median age at presentation was 45 (range, 24-58 years) and TIO was present in three cases. Four tumors involved soft tissue and one involved bone. Four out of the five tumors in our series were initially misdiagnosed. Three tumors were ultimately categorized as malignant PMT (two patients developed metastatic disease). FGFR1 translocation was present in two out of four cases and remained unknown in one case. In summary, we report on five cases of PMTs arising in the head and neck and confirm utility of FGFR1 FISH in the diagnosis of a subset of PMT.

Phosphaturic mesenchymal tumor is an uncommon cause of a paraneoplastic syndrome that can be associated with osteogenic osteomalacia. This tumor most commonly occurs in middle-aged men and women. We report a rare case of a phosphaturic mesenchymal tumor in a 16-year-old girl with multiple fractures as a result of severe osteoporosis. CT and MRI showed a mass arising from the tibia.

Tumor-induced osteomalacia (TIO) is a paraneoplastic syndrome resulting in renal phosphate wasting and decreased bone mineralization. TIO is usually induced by small, slowly growing tumors of mesenchymal origin (phosphaturic mesenchymal tumor mixed connective tissue variant [PMTMCT]). Nonspecific symptoms including fatigue, bone pain, and musculoskeletal weakness make the diagnosis elusive and often lead to a delay in treatment. The prognosis of TIO is excellent following complete resection of the neoplasm, which leads to the rapid and complete reversal of all symptoms. If the tumor cannot be detected, treatment relies on supplementation with phosphate and active vitamin D compounds. Subsequent radiotherapy in case of incompletely resected tumors or definitive radiotherapy in unresectable tumors is an important treatment option to avoid recurrence or metastasis even though this occurs rarely. Due to the risk of recurrence or late metastases, long-term monitoring is required even in TIO patients diagnosed with a benign tumor.

Background: Tumor-induced osteomalacia is a paraneoplastic syndrome resulting in renal phosphate wasting and decreased bone mineralization. Phosphaturic mesenchymal tumors represent a rare etiology of tumor-induced osteomalacia. Nonspecific symptoms of fatigue, bone pain, and musculoskeletal weakness make the diagnosis elusive and lead to a delay in surgical treatment., Questions/purposes: In this case series, the following three questions were asked: (1) How do the clinical presentation and features of phosphaturic mesenchymal tumors delay the diagnosis? (2) What is the clinical course after surgical treatment of phosphaturic mesenchymal tumors? (3) How frequently do phosphaturic mesenchymal tumors recur and are there factors associated with recurrence?, Methods: This study retrospectively reviewed the cases of five adults diagnosed and treated for phosphaturic mesenchymal tumors. Patients were identified through an internal orthopaedic oncology database with clinical, surgical, and histologic data obtained through a systematic chart review., Results: Five patients presented with a long-standing history of osteomalacia, generalized fatigue, pain, and weakness before the diagnosis was reached at an average of 7.2 years (range, 2-12 years) after initial symptom onset. The diagnosis appeared to be delayed owing to the cryptic medical presentation, difficulty in locating tumor by imaging, and confirming histologic appearance. Two patients treated with wide surgical resection did not experience recurrence compared with three patients who did show recurrent signs and symptoms after marginal excision. A postoperative increase in fibroblast-derived growth factor-23 was associated with recurrent disease., Conclusions: Although uncommon, the diagnosis of phosphaturic mesenchymal tumor should be considered in any patient who presents with hypophosphaturic osteomalacia and no other physiologic cause. Definitive treatment is early, wide surgical resection.

Context: Tumor-induced osteomalacia is a rare condition usually caused by benign mesenchymal tumors. When the tumor can be found, patients are usually managed by wide excision of the tumor., Objective: We report a 51-yr-old male with clinical and biochemical evidence of tumor-induced osteomalacia caused by a mesenchymal tumor in the right iliac bone. He declined surgery and appears to have been successfully managed by computed tomography-guided percutaneous ethanol ablation and percutaneous cryoablation., Results: Our patient appears to have had an excellent clinical and biochemical response to computed tomography-guided percutaneous ethanol ablation and percutaneous cryoablation. We found one prior case of image-guided ablation using radiofrequency ablation for tumor-induced osteomalacia., Conclusions: Although the standard treatment for tumor-induced osteomalacia is wide excision of the tumor, image-guided ablation may be an option in patients who cannot have appropriate surgery or who decline surgery.

Phosphaturic mesenchymal tumor of mixed connective tissue type is a rare, histologically distinctive mesenchymal neoplasm associated with tumor-induced osteomalacia resulting from production of the phosphaturic hormone fibroblast growth factor 23. Because of its rarity, specific genetic alterations that contribute to the pathogenesis of these tumors have yet to be elucidated. Herein, we report the abnormal karyotypes from 2 cases of confirmed phosphaturic mesenchymal tumor of mixed connective tissue type. G-banded analysis demonstrated the first tumor to have a karyotype of 46,Y,t(X;3;14)(q13;p25;q21)[15]/46XY[5], and the second tumor to have a karyotype of 46, XY,add(2)(q31),add(4)(q31.1)[2]/92,slx2[3]/46,sl,der(2)t(2;4)(q14.2;p14),der(4)t(2;4)(q14.2;p14),add(4)(q31.1)[10]/46,sdl,add(13)(q34)[4]/92,sdl2x2[1]. These represent what is, to our knowledge, the first examples of abnormal karyotypes obtained from phosphaturic mesenchymal tumor of mixed connective tissue type., (Copyright © 2012 Elsevier Inc. All rights reserved.)

Objective: We describe the first reported case of a phosphaturic mesenchymal tumour, mixed connective tissue variant, invading the temporal bone., Case Report: A female patient presented with increasing deafness. On examination there appeared to be a mass behind an intact tympanic membrane. Further radiological investigation showed a vascular mass occupying the middle ear, mastoid and internal auditory meatus. This was surgically resected and revealed to be a benign phosphaturic mesenchymal tumour, mixed connective tissue variant. The tumour recurred a year later, presenting as facial nerve palsy. A revision procedure was carried out; the tumour was excised with the sacrifice of a segment of the facial nerve, and a facial-hypoglossal nerve anastomosis was performed., Conclusion: This case report highlights the occurrence of this benign but sometimes aggressive tumour, of which both clinicians and pathologists should be aware. Early recognition of the condition remains of utmost importance to minimise the debilitating consequences of long-term osteomalacia in affected patients, and to prevent extracranial and intracranial complications caused by the tumour.

Phosphaturic mesenchymal tumor (PMT) is a rare and distinctive tumor almost always associated with oncogenic osteomalacia. This tumor is often misdiagnosed due to its widely varied histomorphological spectrum. More recently the term PMT or its variants has been used whatever the histomorphological features. Herein, we present a case of a 32-year-old woman who presented with a 2-year history of oncogenic osteomalacia. The clinical examination failed to detect any tumor. The F-18 FDG PET scan and subsequent MRI revealed a tumor in the soft tissues of the right popliteal fossa. The histological features resembled a chondromyxoid fibroma (CMF), a feature documented only in two cases so far.

Tumor-induced osteomalacia (TIO), or oncogenic osteomalacia (OOM), is a rare acquired paraneoplastic disease characterized by renal phosphate wasting and hypophosphatemia. Recent evidence shows that tumor-overexpressed fibroblast growth factor 23 (FGF23) is responsible for the hypophosphatemia and osteomalacia. The tumors associated with TIO are usually phosphaturic mesenchymal tumor mixed connective tissue variants (PMTMCT). Surgical removal of the responsible tumors is clinically essential for the treatment of TIO. However, identifying the responsible tumors is often difficult. Here, we report a case of a TIO patient with elevated serum FGF23 levels suffering from bone pain and hypophosphatemia for more than three years. A tumor was finally located in first metacarpal bone by octreotide scintigraphy and she was cured by surgery. After complete excision of the tumor, serum FGF23 levels rapidly decreased, dropping to 54.7% of the preoperative level one hour after surgery and eventually to a little below normal. The patient's serum phosphate level rapidly improved and returned to normal level in four days. Accordingly, her clinical symptoms were greatly improved within one month after surgery. There was no sign of tumor recurrence during an 18-month period of follow-up. According to pathology, the tumor was originally diagnosed as "lomangioma" based upon a biopsy sample, "proliferative giant cell tumor of tendon sheath" based upon sections of tumor, and finally diagnosed as PMTMCT by consultation one year after surgery. In conclusion, although an extremely rare disease, clinicians and pathologists should be aware of the existence of TIO and PMTMCT, respectively.

Tumor-induced osteomalacia (TIO) is a rare paraneoplastic syndrome that results in renal phosphate wasting with hypophosphatemia. In most cases, the underlying cause of TIO is a small mesenchymal neoplasm that is often difficult to detect, resulting in delayed diagnosis. One such neoplasm is the phosphaturic mesenchymal tumor, mixed connective tissue variant (PMTMCT), an unusual entity with unique morphologic and biochemical features. Most of these tumors are found at appendicular sites with only rare cases reported in the jaws. We describe a PMTMCT involving the mandible in a patient with a protracted history of osteomalacia. A review of the current literature is provided with emphasis on the clinical and histologic features, etiopathogenesis, and management of PMTMCT in the setting of TIO.

Osteomalacia induced by tumor is a rare phenomenon in which the resection of tumor is followed by dramatic amelioration of clinical signs and symptoms. We hereby report a case of a 66 years old male who presented with features of osteomalacia in which the characteristic clinical presentation was associated with the phosphaturic mesenchymal tumor, mixed connective tissue variant. The case is reported for its rarity.