Oncogenic osteomalacia is an unusual and rare clinicopathologic syndrome characterized by mesenchymal tumors that apparently produce osteomalacia and biochemical abnormalities consisting of hypophosphatemia, normocalcemia, and increased levels of alkaline phosphatase. We collected from the Mayo Clinic files and from our consultation files the records for 17 cases of osteomalacia associated with bone lesions. There were five cases of fibrous dysplasia, three of hemangiopericytoma, and two of phosphaturic mesenchymal tumor. There was one case each of osteosarcoma, chondroblastoma, chondromyxoid fibroma, malignant fibrous histiocytoma, giant cell tumor, metaphyseal fibrous defect, and hemangioma. In this study we can figure out that the most common characteristic histologic features of our cases were hemangiopericytomatous vascular proliferation, fine lace-like stromal calcification, and stromal giant cells. In most of the cases, the clinical and biochemical symptoms and signs resolved soon after complete resection of the lesion. When the lesion recurred or metastasized, the symptoms and signs also recurred.
Adolescent ; Adult ; Aged ; Bone Neoplasms/classification/*complications/diagnosis ; Child ; Child, Preschool ; Female ; Fibrous Dysplasia of Bone/classification/*complications/diagnosis ; Follow-Up Studies ; Human ; Male ; Middle Age ; Osteomalacia/*etiology/pathology

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.
Bone Neoplasms ; blood ; complications ; diagnostic imaging ; pathology ; surgery ; Female ; Fibroblast Growth Factors ; blood ; Follow-Up Studies ; Humans ; Hypophosphatemia ; blood ; diagnostic imaging ; etiology ; pathology ; surgery ; Mesenchymoma ; blood ; complications ; diagnostic imaging ; pathology ; surgery ; Metacarpal Bones ; Middle Aged ; Neoplasms, Connective Tissue ; blood ; complications ; diagnostic imaging ; pathology ; surgery ; Osteomalacia ; blood ; diagnostic imaging ; etiology ; pathology ; surgery ; Phosphates ; blood ; Radiography

Actins ; metabolism ; Bone Neoplasms ; blood ; complications ; diagnostic imaging ; pathology ; surgery ; Diagnosis, Differential ; Female ; Humans ; Hypophosphatemia ; blood ; etiology ; Ilium ; Mesenchymoma ; blood ; complications ; diagnostic imaging ; pathology ; surgery ; Middle Aged ; Osteomalacia ; blood ; etiology ; Phosphates ; blood ; Platelet Endothelial Cell Adhesion Molecule-1 ; metabolism ; Tomography, X-Ray Computed