Phosphaturic mesenchymal tumor: management and outcomes of ten patients treated at a single institution.

BACKGROUND: Phosphaturic mesenchymal tumor (PMT) is a rare tumor that causes tumor-induced osteomalacia. Patients present with non-specific symptoms secondary to renal phosphate wasting and decreased bone mineralization. We sought to assess: (1) What are the common presenting features, laboratory and imaging findings, histologic findings of phosphaturic mesenchymal tumors? (2) What are the available treatment strategies for phosphaturic mesenchymal tumors and their long-term outcomes in terms of local recurrence and symptom control after treatment? METHODS: We retrospectively identified patients with a histologic diagnosis of PMT located in the axial or appendicular skeleton, or surrounding soft tissues. A total of 10 patients were finally included in our study. RESULTS: Median tumor size was 1.9 cm (range, 1.1 to 6.1) and median time from symptom onset to diagnosis was 3 years (range, 0.5 to 15 years). All patients but one presented with hypophosphatemia (median 1.9 mg/dL, range 1.2 to 3.2). Pre-operative FGF-23 was elevated in all cases (median 423.5 RU/mL, range 235 to 8950). Six patients underwent surgical resection, three were treated percutaneously (radiofrequency ablation or cryoablation), and one refused treatment. Only one patient developed local recurrence and no patients developed metastatic disease. At last follow-up, nine patients showed no evidence of disease and one was alive with disease. CONCLUSION: Phosphaturic mesenchymal tumor is a rare tumor presenting with non-specific symptoms. Surgery is the standard treatment when negative margins can be achieved without significant morbidity. In patients with small tumors in surgically-inaccessible areas, radiofrequency ablation or cryoablation can be performed successfully.

Phosphaturic mesenchymal tumor: Clinicopathological features with outcomes in 10 patients with review of literature.

BACKGROUND: Phosphaturic mesenchymal tumors (PMTs) are rare mesenchymal tumors, associated with long-standing, non-specific but often debilitating symptoms in the affected patients. These tumors display characteristic histopathological features and in case, identified timely, can be a boon for patients, given an excision is completely curative. AIMS: To evaluate the clinical and histopathological features of 10 PMTs, diagnosed at our institution, along with clinical outcomes in those patients. MATERIALS AND METHODS: This was a retrospective study, wherein 10 PMTs, diagnosed from January 2013 to July 2022, were included. RESULTS: The average age at the time of diagnosis was 40 years with an M:F ratio of 4:1. Clinical features included lumps, weakness, bone pain, difficulty in moving and walking, and pathologic fractures. The biochemical analysis showed normal serum calcium levels (average = 9.5 mg/dL), with low serum phosphorus (average = 2.2 mg/dL) and raised serum fibroblast growth factor 23 (FGF23) levels, in all the cases, wherever available. On histopathology, all tumors showed cells arranged in a hemangiopericytomatous pattern, including oval to short spindle forms. Multinucleate giant cells were present in nine tumors, and characteristic "grungy calcifications" was observed in eight tumors. Prominent pseudo cystic spaces were seen in eight tumors. A significant number of mitotic figures and tumor necrosis were not seen in any tumor. In five cases where follow-up was available, there was complete resolution of symptoms post-resection with no recurrence or metastasis. All those patients were free of disease until the last follow-up. CONCLUSION: This constitutes the first largest comprehensive study on these rare tumors from our country. PMTs can be diagnosed based on certain histopathological features and correlation with clinicoradiological and biochemical findings. These are invariably benign neoplasms. Patients are relieved of their debilitating symptoms after adequate surgical tumor resection. Therefore, their correct and timely diagnosis is crucial.

Sinonasal phosphaturic mesenchymal tumour: radiation oncologist's perspective.

Tumour-induced osteomalacia is a rare cause of osteomalacia, the majority of which is of mesenchymal origin. Oncogenic osteomalacia is a potentially curable condition caused by phosphaturic mesenchymal tumours. We present the case of a woman in her 30s with a sinonasal phosphaturic mesenchymal tumour, treated with surgical excision followed by adjuvant intensity-modulated radiotherapy and subsequent adjuvant chemotherapy. The patient experienced minimal adverse effects during radiation. There was good local control and cosmetic outcomes with no radiation-related toxicity at a follow-up period of 32 months.

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.

[Fibrocartilaginous mesenchymoma: a clinicopathological analysis of four cases].

Objective: To investigate the clinical, radiological, histological and molecular features and the differential diagnosis of fibrocartilaginous mesenchymoma (FM). Methods: Four cases of FM diagnosed in the Department of Pathology, the Sixth People's Hospital Affiliated to Shanghai Jiaotong University School of Medicine from 2020 to 2022 were analyzed. Related literature was also reviewed. Results: Case 1 was a 10-year-old girl with bone destruction in the sacrum and L5 articular processes revealed by CT scan. Case 2 was a 7-year-old girl with an aggressive lesion in her right distal ulna. Case 3 was an 11-year-old boy with a lesion in the metaphysis of his left proximal tibia. Case 4 was an 11-year-old boy with bone destruction in the distal portion of a radius. Microscopically, the four tumors all consisted of numerous spindle cells, hyaline cartilage nodules, and bone trabeculae. The hypocellular to moderately cellular spindle cell component contained elongated cells with slightly hyperchromatic, mildly atypical nuclei arranged in bundles or intersecting fascicles. Benign-appearing cartilaginous nodules of various sizes and shapes were scattered throughout the tumors. There were areas mimicking epiphyseal growth-plate characterized by chondrocytes arranged in parallel columns and areas of enchondral ossification. The stroma was rich in mucus in case 1. Mutation of GNAS and IDH1/IDH2 and amplification of MDM2 gene were not found in any of the three tested cases. Conclusions: FM is very rare and tends to affect young patients. It most frequently occurs in the metaphysis of long tubular bones, followed by the iliac-pubic bones and vertebrae. FM is characterized by a mixed population of spindle cells, hyaline cartilage nodules and trabeculae of bone, without specific immunophenotypes and molecular alternations. As a borderline, locally aggressive neoplasm, surgical removal with a wide margin is generally the treatment of choice for FM.

Fibrocartilaginous mesenchymoma of pelvis-a potential diagnostic pitfall.

Fibrocartilaginous mesenchymoma (FM) is a rare bone tumor mimicking other fibrocartilaginous lesions on imaging and histologically. Hence, it is difficult to diagnose this entity especially on small biopsies. In this article, we report a case of FM mimicking desmoplastic fibroma on biopsy. A 36-year-old male presented with pain in the left hip. Imaging showed a large expansile lytic lesion involving the acetabulum and pubis. The differential diagnosis was suggestive of giant cell tumor, aneurysmal bone cyst, intraosseous desmoplastic fibroma, and chondrosarcoma. Biopsy revealed a low-grade spindle cell lesion with no evidence of osteoid or chondroid matrix. The lack of cartilaginous nodules in the biopsy prompted a preoperative diagnosis of desmoplastic fibroma. The excised mass showed bland spindle cell proliferation, benign cartilage nodules, and epiphyseal plate-like enchondral ossification suggestive of fibrocartilaginous mesenchymoma. Negative immunostaining for SATB2, CDK4, and MDM2 ruled out low-grade central osteosarcoma. Though GNAS mutations were not performed in this case, rimming of the bony trabeculae at the periphery of the epiphyseal growth plate-like cartilaginous nodule ruled out fibrous dysplasia. The absence of cartilaginous component misleads the diagnosis preoperatively in small biopsies.

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.

Intracranial phosphaturic mesenchymal tumors. A case report and review of literature.

Most osteomalacia-inducing tumors (OITs) are phosphaturic mesenchymal tumors (PMTs) that secrete fibroblast growth factor 23 (FGF23). These tumors usually occur in the bone and soft tissues, and intracranial OITs are rare. Therefore, intracranial OIT is difficult to diagnose and treat. This paper presents a case of intracranial OIT and shows a review of previous cases. A 45-year-old man underwent nasal cavity biopsy and treatment with active vitamin D3 and neutral phosphate for hypophosphatemia. Amplification of FGF23 mRNA level within the tumor was detected. Subsequently, the surgical specimen was diagnosed with a PMT and was considered the cause of the patient's osteomalacia. The patient was referred to a neurosurgery department for the excision of the intracranial tumor extending to the nasal cavity. After tumor removal, the serum levels of FGF23 and phosphorus were normalized as compared to preoperative those. The patient remains disease-free, without additional treatment, approximately 10 years after surgery, with no tumor recurrence. As per the literature, intracranial OITs usually occur in patients aged 8-69 years. Bone and muscle pain are major complaints. Approximately 60% of the patients reported previously had symptoms because of intracranial tumors. In some cases, it took several years to diagnose OIT after the onset of the osteomalacia symptoms. Laboratory data in such cases show hypophosphatemia and elevated FGF23 levels. Because FGF23 levels are associated with the severity of osteomalacia symptoms, total tumor resection is recommended. PMT and hemangiopericytoma (HPC) are histologically similar, but on immunochemistry, PMT is negative for signal transducer and activator of transcription 6 (STAT6), whereas HPC is positive. FGF23 amplification is seen in PMTs but not in HPCs. Therefore, the analysis of FGF23 and STAT6 was helpful in distinguishing PMTs from HPCs. In cases of hypophosphatemia and osteomalacia without a history of metabolic, renal, or malabsorptive diseases, the possibility of oncogenic osteomalacia should be considered.

Ectomesenchymal Chondromyxoid Tumor: A Rare Association With an Asymmetrical Soft Palate Cleft.

Ectomesenchymal chondromyxoid tumor (ECT) is a rare oral lesion first described by Smith et al. in 1995. These tumors are typically painless, slow growing and benign masses occurring predominantly on the anterior tongue dorsum. Prior to this seminal report, many ECTs may have been misdiagnosed due to the histological similarities with other lesions. Immunohistochemical stains aid in definitive diagnosis of an ECT. A total of 39 papers since published have reported 96 patients with ECT. Most lesions involve the anterior aspect of the tongue, with only 6 occurring in the posterior tongue and 2 involving the hard palate. ECTs are considered to develop from ectomesenchymal cells of neural crest cells that have migrated to the tongue during embryological development. This paper is of a rare case of ECT of the posterolateral tongue occurring in association with an unusual asymmetrical soft palate cleft. It is postulated that since the tongue develops before the formation of the soft palate, an ECT lesion occurring on the posterior aspect may have a causal contribution to the development of the soft palate cleft.

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.

Tumor mesenquimático fosfatúrico de pelvis: abordaje multidisciplinario / Phosphaturic mesenchymal tumor of the pelvis: A multidisciplinary approach

El tumor mesenquimático fosfatúrico es una entidad clinicopatológica sumamente infrecuente. Además de provocar dolor óseo insidioso y polimialgias, se acompaña de alteraciones del metabolismo fosfocálcico de difícil manejo clínico. El abordaje multidisciplinario resulta la clave del éxito en esta enfermedad. Presentamos una paciente de 52 años de edad con antecedente de tumor mesenquimático fosfatúrico en la hemipelvis derecha con extensión a la cadera homolateral de 10 años de evolución. Clínicamente presentaba osteomalacia oncogénica (hipofosfatemia e hiperfosfaturia) que no se corregía, pese a un agente de última generación, el burosumab, un inhibidor del factor de crecimiento fibroblástico 23, que aumenta la reabsorción tubular renal de fosfatos. En un comité multidisciplinario, se decidió la resección con márgenes oncológicos y se logró una mejoría clínica franca. Comunicamos este caso, debido a que es un cuadro infrecuente. Nivel de Evidencia: IV

Phosphaturic mesenchymal tumor (PMT) is an infrequent clinicopathological entity. It presents insidious bone pain and polymyalgia, accompanied by alterations in calcium and phosphorus metabolism that are difficult to resolve clinically. A multidisciplinary approach is a key to success in this pathology. We present the case of a 52-year-old female patient with a 10-year history of PMT in the right hemipelvis with ipsilateral hip extension. From the clinical point of view, she presented oncogenic osteomalacia (hypophosphatemia and hyperphosphaturia) that did not correct despite being administered the latest generation medication, burosumab, an FGF-23 inhibitor that increases renal tubular phosphate reabsorption. Resection with oncological margins was decided by a multidisciplinary committee resolving her clinical condition. Due to the rarity of this pathology, we decided to report the case. Level of Evidence: IV

[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.

Primary uterine ectomesenchymoma harboring a DICER1 mutation: case report with molecular analysis.

Ectomesenchymoma is an exceedingly rare biphasic malignant tumor characterized by the presence of mesenchymal and neuroectodermal elements. The majority of patients are infants or children. We describe the first case of this entity diagnosed as a primary uterine tumor. A 72-year-old female presented with post-menopausal bleeding. Dilatation and curettage showed irregular mesenchymal proliferation of uncertain nature. In the hysterectomy specimen, a myxoid spindle cell tumor with areas of skeletal muscle and neural differentiation was found in the uterus, with direct invasion of the small intestine, and biphasic differentiation into rhabdomyosarcoma and ganglioneuroblastoma was unequivocally seen in a lymph node metastasis. The morphological findings were validated by immunohistochemistry. Massive parallel sequencing identified TP53, PTEN, and DICER1 mutations in the tumor. This report describes the presence of ectomesenchymoma in an unusual primary organ and in an uncharacteristic age and presents novel data regarding the genetic characteristics of this tumor.

Surgical margin for phosphaturic mesenchymal tumors in soft tissues: An analysis of the radiological histopathological correlation.

BACKGROUND: Phosphaturic mesenchymal tumors primarily cause tumor-induced osteomalacia, a rare paraneoplastic syndrome, and half occur in soft tissues. There are few reports about the surgical margins of these tumors. This study aimed to clarify the optimal surgical margin for phosphaturic mesenchymal tumors by analyzing radiological and histopathological features. METHODS: This study included eight cases, seven primary and one recurrent, of tumor-induced osteomalacia caused by soft-tissue phosphaturic mesenchymal tumors that were surgically treated between January 2000 and January 2019. We evaluated the radiological and histopathological features of all tumors and investigated the correlation of these features, the surgical margin, and recurrence of hypophosphatemia. RESULTS: The tumors were located in superficial (n = 5) and deep (n = 3) tissues. Six of the eight tumors had a clear boundary, but five had an irregular margin. Three tumors had a hypointense rim on T2-weighted images, indicating fibrous tumor encapsulation. Histopathological analysis revealed infiltrative growth in six of the eight tumors, which correlated with an irregular margin seen on imaging. Although there was no recurrence in patients treated with an intended wide margin >1 cm, one of the three patients treated with marginal tumor resection experienced a recurrence of hypophosphatemia, with histopathological analysis showing infiltration of subcutaneous fat. In contrast, two tumors with clear boundaries, regular margins, and fibrous capsule seen on imaging, had no infiltrative growth and were cured by marginal resection. In one recurrent case, tumor infiltration was observed in the previous surgical scar, which was not detected on preoperative imaging. CONCLUSIONS: Soft-tissue phosphaturic mesenchymal tumors with an irregular boundary seen on imaging tend to be infiltrative, especially into subcutaneous fat, and should be treated by at least a 1-cm wide margin resection. Tumors with a fibrous capsule with clear and regular margins are cured by marginal margin resection. These findings could inform surgeons' decisions regarding the resection of soft-tissue phosphaturic mesenchymal tumors.

Tumor-Induced Osteomalacia Caused by a Phosphaturic Mesenchymal Tumor of the Sole Presenting as a Crippling Illness in a Postmenopausal Woman.

Tumor-induced osteomalacia, a rare and intriguing paraneoplastic syndrome that is usually caused by a phosphaturic mesenchymal tumor, leads to severe pain and hypophosphatemia. However, during clinical practice, most patients suffer from significant delay of diagnosis and treatment because the symptoms are similar to those of some very common diseases, such as osteoporosis and osteoarthritis. Moreover, physical complaints from postmenopausal women usually exacerbate the possibility of such delays. We describe a case of a postmenopausal woman with crippling bone pain and weakness, who had been diagnosed with a case of simple osteoporosis and osteoarthritis for 3 years, even with fine-needle aspiration biopsy of the offending phosphaturic mesenchymal tumor. After surgical removal of the 2 × 3-cm2 tumor in her sole, we observed immediate relief of her systemic symptoms, with visual analogue scale improvement from 5 of 10 preoperatively to 2 of 10 5 days after surgery. There were no signs of recurrence during 2-year follow-up. This case highlights the significance of thorough history-taking as a fundamental tool for diagnosis even in the era of advanced technology, and that the awareness of tumor-induced osteomalacia should be raised. Otherwise, such a small localized soft tissue mass would seldom be associated with the severe systemic symptoms.

An ectomesenchymal chondromyxoid tumour on the lateral border of the tongue.

Ectomesenchymal chondromyxoid tumour (ECT) is an extremely rare intraoral mesenchymal tumour. Most of these tumours have been identified on the anterior aspect of the dorsal surface of the tongue. ECT is difficult to diagnose because of its rarity. We report a case of ECT arising on the lateral border of the tongue in a 67-year-old woman. The tumour, measuring 20 × 10 mm in size, was surgically removed. Histopathologically, the tumour was composed of small polygonal cells arranged in sheets, with a myxoid or hyalinized stroma. The tumour boundary was clear; however, the tumour showed a multinodular structure expanding along the tongue surface without obvious capsule. Careful examination revealed the tumour nodule to be spreading in a skip lesion-like fashion away from the main part of the tumour in the striated muscle layer. Although there was no evidence of recurrence at 18 months after the surgery, our observations suggest that surgery for ECT resection with a safety margin is more appropriate than enucleation.