Missed brown tumors in a young adult with decreased bone density

Brown tumors, a benign osteolytic process, are most commonly caused by hyperparathyroidism. Multiple bone involvement is relatively rare. There are many similarities in the radiologic and histological features of brown tumors and giant cell tumors (GCTs) of bone. Differentiation between the two lesions is dependent upon evaluation of serum biochemistry including serum calcium, phosphorous, and intact parathyroid hormone (I-PTH) levels. Herein, the case of a 32-year-old man with multiple osteolytic lesions of the left tibia and fibula as well as the fourth metacarpal bone of the left hand, previously misdiagnosed with multiple GCTs, is presented. Based on the radiographic findings and biochemistry results in a young adult patient, brown tumor was suspected and subsequently definitively diagnosed.