Brown tumor in the pterygopalatine fossa with maxillary and sphenoidal involvement: a rare case report and literature review.

Brown tumors are rare focal giant-cell lesions resulting from the direct effects of parathyroid hormone (PTH) on bone tissue in hyperparathyroidism. Brown tumors most commonly affect long bones, pelvis, and ribs, whereas craniofacial involvement is uncommon, with pterygopalatine fossa involvement being exceedingly rare. This report presents a case of a 13-year-old girl with a rapidly progressing lesion in the pterygopalatine fossa, with involvement of the sphenoid and maxilla. The patient exhibited significant facial pain and V2 paresthesia, with imaging studies suggesting differential diagnoses such as craniopharyngioma and glioma. Pre-operative digital subtraction angiography ruled out highly vascular lesions, and the patient underwent complete tumor resection via an expanded endoscopic transnasal approach. Histopathological evaluation initially revealed a solid-variant aneurysmal bone cyst (ABC). Nevertheless, routine postoperative laboratory evaluation incidentally detected a significant increase in PTH and hypercalcemia, prompting further pathological reassessment and confirming the diagnosis of a brown tumor. Finally, the patient underwent a parathyroidectomy, followed by further management and regular follow-ups. This case highlights the diagnostic challenges posed by the histopathological overlap between brown tumors and other giant-cell lesions, such as ABCs and giant-cell tumors, particularly in their rare presentation in the pterygopalatine fossa. The choice of surgical approach was guided by the lesion's location, symptom severity, and rapid progression, demonstrating the utility of ipsilateral transmaxillary endoscopic techniques in accessing complex anatomical regions. Furthermore, this case underscores the importance of routine calcium and PTH testing in preoperative evaluations of cranial bone lesions to prevent potential misdiagnosis and ensure accurate, effective, and timely management.