Brown Tumor of the Facial Bones in a Patient with Hyperparathyroidism Due to Chronic Renal Failure: A Case Report

Brown tumors are benign, non-neoplastic lesions found in 1.5% to 1.7% of patients with end-stage chronic kidney disease. They are classic manifestations of hyperparathyroidism (HPT): primary due to parathyroid disorders, secondary from non-parathyroid causes leading to chronic hypersecretion, and tertiary due to autonomous secretion in longstanding secondary HPT. These lesions can be monostatic or polystatic, primarily affecting the ribs, pelvis, femur, and mandible, with a higher prevalence in young women. Maxillary involvement is rare, occurring in about 4.5% of cases. We report the case of a 22-year-old female patient with a history of chronic kidney disease since the age of 7, who presented a bilateral painless mandibular swelling. Laboratory evaluation revealed that the patient had secondary hyperparathyroidism. Due to the mandibular swelling, a facial CT scan was performed that revealed multiple lytic lesions that were expansive, causing cortical bone blowout and rupture, with visible intralesional trabeculations in the frontal bone, the outer wall of the left orbit, right temporal region, condyles, mandibular angles, and the maxillomandibular dental arches. There was diffuse bone involvement predominantly showing ground-glass opacity, with cortical-medullary dedifferentiation and bone hypertrophy affecting the facial mass, skull vault, and base of the skull. After clinical and radiological evaluation, the patient underwent an excisional biopsy of the hemimandibular right lesion, and it was diagnosed histologically as a brown tumor. In the first year of postoperative follow-up, the patient reported rib pain, prompting a cervical-thoracic CT scan. The scan showed multiple lytic bone lesions with cortical rupture in the clavicles, scapulae, right humeral head, and ribs, along with diffuse bone changes indicating dedifferentiation and hypertrophy in the vertebral and rib areas. Brown tumors pose a diagnostic challenge due to their association with ...