Diagnosis and Treatment of Brown Tumor in the Femur Induced by Parathyroid Carcinoma: A Case Report.

Brown tumors are rare destructive bone lesions caused by hyperparathyroidism. As their clinical symptoms, radiographic findings, and laboratory results closely mimic those of metastatic tumors or multiple myeloma, the diagnosis may often be mistaken. We report a case of a 61-year-old woman with brown tumors in both femurs due to parathyroid carcinoma. The patient presented with multiple osteolytic lesions that caused pain in the right thigh. Whole-body computed tomography (CT), including the neck, suspected a parathyroid tumor, and a biopsy of the bone lesion revealed no malignancy. Following parathyroidectomy, she was diagnosed with a brown tumor with hyperparathyroidism due to a very rare parathyroid carcinoma. Although the right femoral lesion was indicated as an impending fracture, conservative treatment was performed because of the instability of her general condition after parathyroidectomy and her wishes. Bone remodeling of the right femur progressed, and the patient was ambulatory; however, 9 months postoperatively, the patient fell, developed a pathological fracture, and underwent internal fixation. When multiple osteolytic bone lesions are present, CT imaging of the neck should be performed to determine the possibility of a brown tumor due to parathyroid disease. Bone lesions of brown tumors are known to be naturally cured after treatment for hyperparathyroidism. However, when the lesion of a brown tumor in the femur is an impending fracture, prophylactic internal fixation is recommended aggressively if the patient's general condition permits.