Rare solitary pituitary metastasis of maxillary ameloblastic carcinoma: illustrative case

Abstract

BACKGROUND Ameloblastic carcinoma (AC) is a rare odontogenic carcinoma with histological features resembling ameloblastoma. Metastasis to distant organs and direct expansion into the skull base structures are associated with a poor clinical outcome. This rare case of AC metastasis to the pituitary gland presented without local recurrence at the primary focus of the maxilla. OBSERVATIONS A 47-year-old man had a 2-year history of AC in the right maxilla. Computed tomography for his regular checkup incidentally demonstrated pituitary tumor, rapidly growing over 2 months. He presented with the recent onset of panhypopituitarism and visual field defect. Magnetic resonance imaging showed a large, irregularly shaped intrasellar and suprasellar lesion with chiasmal compression. Endoscopic endonasal transsphenoidal surgery was performed for decompression of the optic apparatus to avoid intracranial spread. Histopathology confirmed metastatic AC, and a genetic panel test confirmed BRAF V600E mutation. Stereotactic radiotherapy (SRT) with the CyberKnife system was administered to the residual tumor. Remarkable tumor shrinkage was obtained, and panhypopituitarism was resolved 12 months later. LESSONS A multidisciplinary treatment strategy including maximal safe resection to avoid dissemination in combination with SRT may be crucial for local control with the preservation of pituitary and visual functions in patients with solitary pituitary metastatic AC.