A 50-Year-Old Man Presenting with Multiple Bone Lesions and a Diagnosis of Phosphaturic Mesenchymal Tumor of the Femur.

BACKGROUND Phosphaturic mesenchymal tumor (PMT) is an extremely rare mesenchymal neoplasm that is commonly seen in bone and soft tissue. It is associated with a paraneoplastic syndrome, oncogenic osteomalacia, due to tumor-induced urinary phosphate wasting. It is demonstrated to be predominantly mediated by fibroblast growth factor 23 (FGF23)/fibroblast growth factor receptor 1 (FGFR1) axis. Clinically, PMT usually presents as a solitary lesion in the bone. The diagnosis of PMT is challenging due to its non-specific clinical manifestation, radiologic findings, and morphological features. CASE REPORT We report the case of a 50-year-old man presenting with multiple lytic bone lesions and associated pathologic fracture of the right femur, clinically suspicious for multiple myeloma or other metastatic malignant process. Resection from the right femur showed a hypercellular lesion composed of oval-to-spindled cells infiltrating the native trabecular bone with admixed multinucleated giant cells. Immunohistochemical (IHC) staining and in situ hybridization (ISH) demonstrated the tumor cells were positive for SATB2, ERG, FGFR1, and FGF23 ISH. DNA and RNA next-generation sequencing showed marked increases in mRNA levels of FGF23 and FGFR1. The constellation of clinicoradiologic, histomorphologic, IHC, and molecular findings supported a diagnosis of primary benign PMT. CONCLUSIONS This case report discusses a patient with PMT presenting with multifocal lesions due to tumor-induced osteomalacia at initial presentation. We hope that this report will increase the awareness of clinician and pathologists of PMT as a differential diagnosis in patients presenting with multifocal lytic bone lesions. In turn, this will prevent misdiagnosis and overtreatment of a typically benign process.

Tumor-induced osteomalacia: An overview.

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.

Phosphaturic mesenchymal tumor: A chondromyxoid fibroma-like type.

Phosphaturic mesenchymal tumor (PMT) is a rare neoplasm that causes tumor-induced osteomalasia (TIO) in most affected patients, usually through the production of fibroblast growth factor 23 (FGF23). This tumor is often misdiagnosed due to its relative rarity and its widely varied histomorphologic spectrum. Here we describe a case of a 78-year-old woman who presented with a left middle tumor without symptoms of TIO. The histological features resembled chondromyxoid fibroma with smudgy calcification in the tumor matrix. In addition, we evaluated FGF23 expression through immunohistochemical study and reverse transcription polymerase chain reaction. PMT with chondromyxoid fibroma features are extremely rare. Examining the expression of FGF23 is useful in the diagnosis of PMT.

Phosphaturic Mesenchymal Tumor Along the Hallux side Inducing a Chronic non-Healing Wound: A Case Report with Literature Review.

Phosphaturic mesenchymal tumor (PMT) is a rare paraneoplastic syndrome characterized by renal phosphate wasting, hypophosphatemia, and bone calcification disorders. Complete surgical resection of the tumor is believed to be the most effective treatment measure. However, the diagnosis of PMT is very difficult because of its insidious and small size, especially, when it appears in subcutaneous tissue with a chronic non-healing wound. We report a rare case of a 38-year-old man with a chronic non-healing wound on the left hallux for approximately eight months. Plain radiographic images and magnetic resonance imaging (MRI) revealed a cystic radiolucent shadow in the left distal phalanx. Bone scan observations also showed increased uptake in the same location. Histologically, this tumor was composed of numerous spindle cells with clusters of giant cells. The serum FGF23 level was significantly higher before surgery, with higher FGF23 levels closer to the tumor. Reverse transcription polymerase chain reaction and immunohistochemistry further confirmed the high expression of FGF23 in tumors. These data suggest that FGF23 may be a potential causative factor of PMT. The serum FGF23 levels might be useful for the diagnosis of PMT and localization of the tumor. The tumor was CD56- and D2 to 40-positive and CD31-negative. The non-healing wound caused by PMT might be attributed to the invasive growth of the tumor, destruction of intercellular junctions, and decrease in the number of endothelial cells.

A Phosphaturic Mesenchymal Tumor Presenting as Reversible Metabolic Myopathy.

Tumor-induced osteomalacia (TIO) is a disorder in which the clinical signs and symptoms of osteomalacia and the biochemical abnormalities of hypophosphatemia, phosphaturia, and low serum levels of 1,25(OH)2 Vitamin D3 are secondary to a neoplasm. A 33-year-old woman presented with musculoskeletal pain and proximal myopathy with a duration of 2.5 years which was treated with Vitamin D supplements. On the basis of the biochemical tests and histopathology, she was reevaluated and found to have TIO secondary to a phosphaturic mesenchymal tumor. The tumor was resected (limb salvage with endoprosthesis), and she had no pain or weakness at followup. The case reminds the readers to consider the possibility of TIO when evaluating patients with isolated hypophosphatemia, which may lead to long-term disability and prolonged morbidity if untreated. Early recognition and diagnosis of TIO is crucial since resection of the tumor usually reverses its manifestations.

Phosphaturic Mesenchymal Tumor.

Phosphaturic mesenchymal tumors (PMTs) are neoplasms associated with tumor-induced osteomalacia. Patients typically present with pathologic fractures in the setting of chronic hypophosphatemic hyperphosphaturic osteomalacia, as well as gradual muscle weakness, bone pain, and difficulty walking. Because of their rarity and nonspecific symptomatology, phosphaturic mesenchymal tumors often go undiagnosed for years. Even when discovered on imaging, the tumors can be diagnostically challenging for radiologists. Phosphaturic mesenchymal tumors often tend to be small and can be located nearly anywhere in the body, and, therefore, can mimic many other tumors. This case highlights the imaging and pathologic markers of a phosphaturic mesenchymal tumor, often found in a patient with tumor-induced osteomalacia.

Phosphaturic Mesenchymal Tumors of the Sinonasal Area and Skull Base: Experience at a Single Institution.

OBJECTIVES: Phosphaturic mesenchymal tumor (PMT) is a rare, polymorphous neoplasm with a highly variable presentation and natural history and unpredictable clinical course. The primary objective was to describe our clinical experience with and management of 4 markedly different cases of sinonasal and skull base PMT. METHODS: A retrospective case series with chart review, and relevant literature review, was performed at a tertiary academic medical center between 1998 and 2020. Adult patients treated for PMTs of the sinonasal area and skull base were included. Our main outcome measures included postoperative laboratory findings and radiological evidence of disease remission. RESULTS: Four patients (2 Males, 2 Females; Mean Age: 63.5 years) with PMTs of the skull base have been managed at our institution since 1998. Patient presentations varied, ranging from severe phosphorus wasting and osteoporosis to symptoms secondary to mass effect, including nasal obstruction and rhinorrhea. All 4 patients were eventually found to have elevated levels of fibroblast growth factor 23. Tumors were located in the sinonasal area (right frontal sinus, right ethmoid sinus, and right nasal cavity, respectively) in 3 patients and in the lateral skull base (right jugular foramen) in 1 patient. All 4 patients underwent complete surgical resection of their tumors. PMT tissue pathology was confirmed in all cases. Gross total resection was achieved in all patients. There was no chemical or radiological evidence of disease recurrence in any patients at follow-up. CONCLUSIONS: The presentation of skull base PMT is variable, and it may mimic other mass pathologies of the head and neck. Complete surgical resection with negative margins is potentially curative.

Phosphaturic Mesenchymal Tumor of the Ankle: A Case Report and Review of the Literature.

We report the case of a phosphaturic mesenchymal tumor of the ankle; an extremely rare lesion that causes osteomalacia via paraneoplastic renal phosphate wasting. A 41-year-old man was referred to plastic surgery with a swelling over the anterior ankle, which had been increasing in size for 1 year. Focused ultrasound assessment was inconclusive, but excision biopsy demonstrated features in keeping with a phosphaturic mesenchymal tumor. Evidence of tumor-induced osteomalacia was subsequently identified on review of historical biochemistry. The patient was followed-up for 1 year with normalization of serum phosphate. In this case report, we present a discussion of the differential diagnosis for foot and ankle soft tissue lesions, and a review of the literature regarding the diagnosis and management of these tumors. Accurate identification of any soft tissue lesion on clinical examination alone is extremely challenging and excision biopsy should be considered in cases of diagnostic uncertainty.

Clinical, morphological and immunohistochemical analysis of 13 cases of phosphaturic mesenchymal tumor - A holistic diagnostic approach.

BACKGROUND: Phosphaturic mesenchymal tumor-mixed connective tissue (PMT-MCT) is a rare tumor characterized clinically by presence of tumor-induced osteomalacia (TIO), subsequent to elevated fibroblastic growth factor 23 (FGF23) levels. This study aims to analyse the morphological spectrum of PMT along with clinico-pathological correlation and immunophenotype profile of this rare tumor. MATERIALS AND METHODS: Detailed histological analysis of all tumors presenting with TIO over past 7 years was done retrospectively. Immunohistochemistry was performed in all cases for SATB2, STAT6, CD34, FGF23, ERG, S100 and smooth muscle actin (SMA). RESULTS: A total of 13 cases were analysed (8 female and 5 male) with mean age of 39.8 years. Five cases were arising from bone while 4 each from soft tissue and nasal cavity/paranasal sinus. All presented with hypophosphatemia, hyperphosphaturia, elevated serum FGF23 and features suggestive of osteomalacia. Histological examination revealed basophilic 'grungy' calcification seen in 7 (53.8%), osteoid formation in 8 (61.5%), chondroid matrix in 4 (30.8%), adipose tissue in 6 (46.2%), osteoclast-like giant cells in 9 (69.2%) and hemangiopericytomatous (HPC like) blood vessels in 7 cases (53.8%). HPC like vessels and adipose tissue were more common in nasal tumors while calcification was more common in tumors arising from bone. All cases showed immunoreactivity for SATB2 and clinical improvement following resection except one case with residual tumor. CONCLUSION: PMT shows varied histological pattern with various matrix components depending on the site of the tumor. Serum FGF-23 is a useful adjunctive marker for diagnosis.

[Diagnosis and surgical treatment of sinonasal phosphaturic mesenchymal tumor].

Objective: To investigate the diagnosis and surgical treatment of sinonasal phosphaturic mesenchymal tumor (PMT). Methods: The medical records of nine patients who had been diagnosed as sinonasal PMT in Department of Otorhinolaryngology Head and Neck Surgery, Shanghai JiaoTong University Affiliated Sixth People's Hospital between January 2015 and May 2020 were collected, including 4 males and 5 females, ranging from 36 to 59 years. The patient's previous history, clinical manifestations, imaging findings, laboratory results, surgical procedure, pathological results and postoperative follow-up data were analyzed by descriptive statistical analysis. Results: All patients presented hypophosphatemia and tumor-induced osteomalacia (TIO) with a disease course of 1 to 19 years. The imaging examination and intraoperative findings identified two cases with peripheral tissue infiltration, two cases with contralateral nasal cavity invasion, and one case with intracranial invasion. Five patients underwent unilateral endoscopic resection while two patients underwent bilateral endoscopic resection, and the remaining two patients underwent unilateral transorbital ethmoid artery ligation plus endoscopic tumor resection and endoscopic combined with transfrontal tumor resection (n=1 each). Expect for one case developed recurrence and intracranial involvement, the other patients achieved clinical remission and no recurrence was observed during the six-month follow-up. Conclusions: The diagnosis of sinonasal PMT needs combination of clinical manifestation, imaging, and pathological findings. Complete surgical excision and long-term postoperative follow-up are imperative.

Clinicopathologic and molecular features of six cases of phosphaturic mesenchymal tumor.

Phosphaturic mesenchymal tumors (PMT) are rare neoplasms characterized by secretion of FGF23, resulting in renal phosphate wasting and osteomalacia. This tumor-induced osteomalacia (TIO) is cured by complete resection; thus, diagnosis is important, particularly on biopsy. Although PMT have a classic histologic appearance of bland spindled cells with conspicuous vascular network and characteristic smudgy basophilic matrix, there is a broad histologic spectrum and variant histologic patterns can make recognition difficult. Recent studies have demonstrated FN1-FGFR1 and FN1-FGF1 gene fusions in PMT; however, approximately 50% of cases are negative for these fusions. We sought to characterize 6 cases of PMT in-depth, compare fusion detection methods, and determine whether alternative fusions could be uncovered by targeted RNA sequencing. Of the 6 cases of PMT in our institutional archive, 3 were not given diagnoses of PMT at the time of initial pathologic examination. We characterized the immunoprofile (SMA, D2-40, CD56, S100 protein, desmin, SATB2, and ERG) and gene fusion status (FN1 and FGFR1 rearrangements by fluorescent in situ hybridization (FISH) and two targeted RNA sequencing approaches) in these cases. Tumors were consistently positive for SATB2 and negative for desmin, with 5/6 cases expressing ERG and CD56. One specimen was acid-decalcified and failed FISH and RNA sequencing. We found FN1 gene rearrangements by FISH in 2/5 cases, and a FN1-FGFR1 fusion by targeted RNA sequencing. No alternative gene fusions were identified by RNA sequencing. Our findings suggest that IHC and molecular analysis can aid in the diagnosis of PMT, guiding excision of the tumor and resolution of osteomalacia.

[Hereditary cancer predisposition syndromes associated with sarcomas]. / Felnottkori szarkómához asszociált örökletes daganatszindrómák.

Based on our current knowledge, 5-10% of all malignancies are part of hereditary cancer syndromes. Although the increasing diagnostic role of molecular genetic testing makes us able to recognize more hereditary cancer patients, the careful exploration of family and clinical history by physicians is still the most important step for the diagnosis. In our review we deal with mesenchymal tumours associated with hereditary syndromes. Sarcomas comprise only 1% of all malignancies, but they often associate with familiar diseases so they can serve as an indicator of these syndromes. The diagnosis of hereditary cancer predisposition syndromes is essential to ensure appropriate therapy and follow-up for our patients.

Successful treatment of tumor-induced osteomalacia causing by phosphaturic mesenchymal tumor of the foot.

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.

Tumour-induced Osteomalacia Secondary to Intracranial Tumours - Report of 2 Cases.

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.

Phosphaturic Mesenchymal Tumor of Soft Tissue of the Foot: Report of a Case With Review of the Literature.

Phosphaturic mesenchymal tumor (PMT) is a rare neoplasm that ectopically secretes fibroblast growth factor 23, a bone cell-derived protein that regulates phosphate homeostasis. The overproduction of fibroblast growth factor 23 causes a paraneoplastic syndrome characterized by hyperphosphaturia, hypophosphatemia, hypovitaminosis D, and vitamin D refractory rickets/osteomalacia, effects that disappear with tumor removal. The PMT may occur in several anatomic regions, mainly in the limbs, usually involving both soft tissue and bone. Acral locations occur in 10% to 15% of the cases, mostly in the feet, with 95 cases reported in this anatomic region to date. We report a case of a PMT in a young adult male who presented in 2007 with the classic constellation of signs and symptoms. A small soft-tissue tumor was detected in his right heel, 3 years after exhaustively seeking for it by various imaging techniques performed at different institutions. Before the tumor was detected, attempts to manage this patient's osteomalacia with phosphate and vitamin D (both calcitriol and ergocalciferol) supplementation were unsuccessful. Following surgical resection, the patient experienced prompt correction of the phosphaturia and gradual reconstitution of his bone mineralization. The pathologic diagnosis was (benign) PMT, mixed connective tissue type. In 2019, 12 years after resection, the patient is asymptomatic, and his bone mineral homeostasis has been restored.

Prognostication in Mesenchymal Tumors: Can We Improve?

Prognostication in mesenchymal tumors can be challenging. They exhibit diverse, and sometimes overlapping, histologic features that are not always predictive of their true behavior. This article highlights examples of both traditional and emerging sarcoma biomarkers.

Practical Application of Cytology and Core Biopsy in the Diagnosis of Mesenchymal Tumors.

Soft tissue neoplasms are increasingly being sampled by core needle biopsy and fine-needle aspiration (FNA), and these small biopsy specimens pose unique diagnostic challenges. Many advances in ancillary testing enable detection of characteristic immunophenotypes and molecular alterations, allowing accurate classification of soft tissue tumors in these small biopsy samples. This review outlines pattern-based diagnostic approaches to core biopsies and FNAs of soft tissue neoplasms, including formulation of practical differential diagnoses and relevant application of ancillary tests.