DOI: https://doi.org/10.36347/sjmcr.2026.v14i11.037

Pages: 2583-2585

Brown tumors are non-neoplastic skeletal lesions associated with hyperparathyroidism. Ethmoidal involvement is rare and may initially present with sinonasal symptoms. A 45-year-old woman presented with left-sided nasal obstruction and frontal headaches lasting six months. Computed tomography demonstrated a 32 × 24 mm expansile osteolytic lesion centered in the left ethmoid air cells. Laboratory investigations revealed hypercalcemia (3.05 mmol/L), hypophosphatemia (0.62 mmol/L), elevated parathyroid hormone (485 pg/mL), and hypercalciuria (11.23 mmol/24 h), with preserved renal function. These findings supported primary hyperparathyroidism. Cervical ultrasonography, computed tomography, and scintigraphy yielded concordant findings suggestive of a large right inferior parathyroid adenoma. The ethmoidal lesion was considered compatible with a brown tumor. Hypercalcemia was controlled with calcitonin and bisphosphonates before minimally invasive right inferior parathyroidectomy. The postoperative course was uneventful. This case emphasizes the importance of assessing calcium and phosphate metabolism and measuring parathyroid hormone when investigating expansile craniofacial bone lesions.