A Case of Tumor-Induced Osteomalacia Associated with an Organizing Hematoma

ABSTRACT Objective: Tumor-induced osteomalacia is a paraneo-plastic syndrome characterized by renal phosphate wasting that results in hypophosphatemia and osteomalacia. Tumor-induced osteomalacia is typically associated with benign mesenchymal tumors arising in the bone and soft tissue. Here, we describe a case of tumor-induced osteomalacia associated with an organizing hematoma. Methods: Medical records were reviewed. Results: A 54-year-old, Asian woman presented with progressive pain in the thighs and pelvis for a year that eventually led to a waddling gait. Laboratory examinations showed hypophosphatemia, hyperphosphaturia, normocalcemia, elevated serum alkaline phosphatase levels, and decreased serum calcitriol levels. The patient's bone mineral density was low, and the bone scan showed increased uptake throughout the skeleton. A bone biopsy contained excessive osteoid. We found a palpable mass on her left flank, which had been detected 2 years previously after doing a hula hoop exercise. Computed tomography showed a heterogeneously enhanced, subcutaneous mass in the left-lateral abdominal wall. We resected the mass and it was identified as a phosphaturic mesenchymal tumor with an organizing hematoma. After surgery, her serum phosphorus level returned to normal, and her thigh and pelvis pain improved. Conclusion: Since a hematoma-associated lesion can be a source of phosphaturic agents, any previous history of injuries should be carefully explored in suspected cases of tumor-induced osteomalacia. Abbreviations: PMT phosphaturic mesenchymal tumor TIO tumor-induced osteomalacia