Brown tumor of the ulna as first manifestation of primary hyperparathyroidism

Brown tumor is one of the skeletal manifestation of hyperparathyroidism. Histologically, brown tumor may be difficult to distinguish from other giant cell lesions and a clinical diagnosis is made based on the association with hyperparathyroidism. A 67-year-old woman presented a pathologic fracture of the right ulna, fever and obnubilation. Laboratory tests revealed hypercalcemia (serum calcium level: 15 mg/dl). Malignancy was suspected but staging was negative. Bone scan revealed areas of increased uptake in the right superior limb and in a rib. A TC-guided biopsy was performed with a pathological diagnosis of osteoclastoma. The mass was surgically removed and the final pathological diagnosis was giant-cell lesion. After surgery, laboratory tests revealed hypercalcemia and elevated intact PTH (1 118.47 pg/ml). 99mTc-sestaMIBI scan revealed a right inferior parathyroid iperactivity. Surgical right inferior parathyroidectomy was performed and the lesion was histopathologically diagnosed as an adenoma. After surgery, serum calcium became normal and i-PTH dropped to 363.97 pg/ml. After 1 year, serum calcium was normal but i-PTH was 204 pg/ml and 99mTc-sestaMIBI revealed a left paratracheal iperactivity. Plain radiographs showed multiple osteolytic lesions and abdominal sonography showed a nephrolitiasis. After 3 years, plain radiographs showed marked regression of the bony lesions. It is necessary to exclude the presence of hyperparathyroidism with ionised calcium and i-PTH before performing a histological diagnosis of giant-cell bone tumor.