7630 Incidental Calvarial Brown Tumor in an ESRD patient with seizures

Abstract Disclosure: K.N. Pereira: None. V. mehta: None. S. Sekaran: None. M. Renzu: None. Brown Tumor [BT], also known as Osteitis fibrosa cystica [OFC], is a rare tertiary manifestation of hyperparathyroidism [HPTH]. BT commonly affects the maxilla/mandible, long bones and spine and presents as lytic bone lesions on imaging. Among the crania-facial bones, the maxilla, palate, temporal bone, nasal cavity, orbital bone and paranasal sinuses are affected. We describe a case of a 37 year old African-American female with extensive medical history including ESRD on hemodialysis who initially presented to the hospital with hypertensive emergency in the setting of 1 week of missed dialysis. During her presentation, she had an unexplained seizure which led to further workup with imaging. CT head revealed findings suspicious of renal osteodystrophy as well as a discrete lucency at the calvarial vertex suggestive of a brown tumor. Endocrinological studies were noted to have very high PTH levels with hypercalcemia, hyperphosphatemia and vitamin D deficiency indicative of tertiary hyperparathyroidism. Based on her clinical presentation, labs and imaging, her bone disease including BT and pathologic fractures, was deemed to be due to tertiary hyperparathyroidism in the setting of ESRD, which were not amenable to surgical intervention. Extensive literature review did not reveal any reported BTs in the calvarial vertex. This case emphasizes on the holistic approach to diagnosis of BTs and underlines that fact that BT can occur in any cortical bone including unusual presentation sites like the calvarial vertex. Presentation: 6/3/2024