Diagnosis of phosphaturic mesenchymal tumor (mixed connective tissue type) by cytopathology

Cytological findings of phosphaturic mesenchymal tumor: Report of a case with summary of prior published cases

Phosphaturic mesenchymal tumor (PMT) is a rare neoplasm causing tumor-induced osteomalacia (TIO) and is characterized by secretion of FGF23, renal phosphate wasting and hypophosphataemia. It can be completely cured by resection and therefore its diagnosis is of utmost importance. Although the histology is well described, there is sparse literature on cytology of PMT and only three cases have been described so far. A 45-year-old lady presented with a non-tender mass in hard palate for 2 years from which fine-needle aspiration was done. The smears were paucicellular and showed bland spindle cells embedded in osteoid-like stromal matrix in a hemorrhagic background. Here we take the opportunity to describe the cytological findings of PMT along with its cytological differentials and a summary of prior published cases.

Oncogenic osteomalacia caused by a phosphaturic mesenchymal tumor of the femur: A case report

BACKGROUND

Oncogenic osteomalacia caused by phosphaturic mesenchymal tumors is very difficult to detect. We report a case of tumor-induced osteomalacia caused by a phosphaturic mesenchymal tumor of the left femur in a middle-aged woman after medical imaging and biopsy.

CASE SUMMARY

A 57-year-old woman presented with progressive bone pain for five years. She was diagnosed with hypophosphatemic osteomalacia, as her laboratory data showed low serum phosphorus and low serum calcium. Her knee joint radiography revealed an osteolytic lesion of the left femur. A computed tomography scan showed mixed density shadows in the left femur. Magnetic resonance imaging of the left femur showed the presence of an oval area with a hypointense signal in T1-weighted magnetic resonance imaging (MRI) and high-low mixed signal in T2-weighted MRI. Biopsy samples revealed the presence of short spindle cells, vascularization, and characteristics of phosphaturic mesenchymal tumors. Tumor resection was performed, and the clinical presentations and laboratory abnormalities were reversed.

CONCLUSION

Diagnosis of oncogenic osteomalacia is difficult due to the varieties and localization of source tumors and absence of pathognomonic biomedical signs. Our case highlights the importance of a combination of medical imaging and biopsy in the diagnosis of oncogenic osteomalacia caused by a phosphaturic mesenchymal tumor.

CT and MR imaging features in phosphaturic mesenchymal tumor-mixed connective tissue: A case report

Phosphaturic mesenchymal tumor-mixed connective tissue (PMT-MCT) is rare and usually benign and slow-growing. The majority of these tumors is associated with sporadic tumor-induced osteomalacia (TIO) or rickets, affect middle-aged individuals and are located in the extremities. Previous imaging studies often focused on seeking the causative tumors of TIO, not on the radiological features of these tumors, especially magnetic resonance imaging (MRI) features. PMT-MCT remains a largely misdiagnosed, ignored or unknown entity by most radiologists and clinicians. In the present case report, a review of the known literature of PMT-MCT was conducted and the CT and MRI findings from three patient cases were described for diagnosing the small subcutaneous tumor. Typical MRI appearances of PMT-MCT were isointense relative to the muscles on T1-weighted imaging, and markedly hyperintense on T2-weighted imaging containing variably flow voids, with markedly heterogeneous/homogenous enhancement on post contrast T1-weighted fat-suppression imaging. Short time inversion recovery was demonstrated to be the optimal sequence in localizing the tumor.

Phosphaturic mesenchymal tumor of the brain without tumor-induced osteomalacia in an 8-year-old girl: case report

Phosphaturic mesenchymal tumor (mixed connective tissue variant) (PMT-MCT) are tumors that may cause tumor-induced osteomalacia and rarely appear intracranially. The authors describe the case of an 8-year-old girl who was found to have PMT-MCT with involvement of the cerebellar hemisphere and a small tumor pedicle breaching the dura mater and involving the skull. This was removed surgically in gross-total fashion without further complication. Histologically the tumor was confirmed to be a PMT-MCT. There was no evidence of tumor-induced osteomalacia. At the 42-month follow-up, the patient is doing well, has no abnormalities, and is free of recurrence. PMT-MCTs are rare tumors that may involve the brain parenchyma. A gross-total resection may be effective to cure these lesions.

Phosphaturic mesenchymal tumor of the tibia with oncogenic osteomalacia in a teenager

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.