Primary hyperparathyroidism with brown tumor mimicking metastatic bone malignancy.

Bone and joint pain are commonly encountered conditions in daily practice. In the elderly, when osteolytic lesions are identified in imaging studies, metastatic bone tumor is the first impression that comes to the clinician's mind. Although the worst-case scenario should be ruled in, other differential diagnoses such as metabolic bone disease should be considered as well. We report a case of brown tumor caused by parathyroid adenoma. The patient had initial presentation of diffuse bone pain and multiple osteolytic lesions on imaging studies similar to metastatic bone tumor. With a systematic approach and awareness of metabolic bone disease, an accurate diagnosis was finally reached. Appropriate treatments, including preventive internal fixation of the impending femoral fracture and surgical excision of the parathyroid adenoma were performed accordingly. The key treatment for the condition was surgical excision of the parathyroid adenoma. After normalization of serum intact-parathyroid hormone level, the bony lesions resolved and required no further orthopedic surgery. The patient is now symptom-free. In addition to suspecting malignancy, the clinician should be highly alert to other possible causes of bony lesions. Brown tumor should be kept in mind during daily practice.