Endocrine Abstracts

Case

Male, 44 y.o., with rigth maxillary tumor of progressive growth for 1 year with local and low back pain. Imaging exams: CT/MRI skull and face: right axial expansive lesion (62×52×46 mm), heterogeneous, multiloculated with bulging of the right orbit inferomedial wall, with a neoplastic aspect. CT pelvis: bone lesions with soft tissue densities in pelvis, heterogeneous L4, with height reduction. Biopsy of the lesion suggesting a brown tumor. Investigation continued with PTH: 998 pg/ml and calcium: 10.4 mg/dl (8.5–10.5 mg/dl), scintigraphy: parathyroid-hyperfunctioning left lower parathyroid and bone-hypercapture, with emphasis on the skull, right scapula, some costal arches, T8, L4, sacroiliac regions, iliac crystals, left pubic branch, left ischium, trochanter of the right femur, proximal third of the left tibia and medial and malleoli right side, DXA Z-score RD -8.0DP. The patient was admitted with severe hypercalcemia (calcium: 14.6 mg/dl), phosphorus 2.4 mgdl, without neurological symptoms. Parathyroidectomy was performed with histological result of adenoma and a significant reduction in PTH levels (29.9 pg/ml) in the immediate postoperative period. In the 6 months of follow-up, he has normalization of calcemia and PTH, significant pain improvement, and gradual reduction of the tumor.

Discussion

Brown tumor appears in hyperparathyroidism, due to the action of PTH, leading to a replacement of bone tissue by dense connective tissue well vascularized, with fusiform and giant cells, areas of hemorrhage with a large amount of hemosiderin pigments and bone trabeculae, forming a very demineralized and fragile area, with a higher risk of fracture. In the initial evaluation of a lesion suggestive of a brown tumor, it is essential to measure the levels of calcium and PTH. Majority of cases of HPT are caused by adenomas (80 to 85%) and the minority due to hyperplasia of the four glands (15%), with 2 to 4% of multiple adenomas and less than 0.5% caused by carcinoma. Differentiation of adenoma and carcinoma by histological/immunohistochemical study takes into account degree of lesion invasion, number of mitoses, trabecular pattern and evaluation of a panel of markers (parafibromine, galactin-3, PGP9.5 and Ki67).

Final comments

It is necessary to emphasize the importance of screening methods and early diagnosis of a systemic disease such as hyperparathyroidism, which can evolve with serious complications, increasing morbidity and mortality.