Rare case of a craniopharyngioma in the prepontine cistern: A case report.

Background: Craniopharyngiomas are rare benign epithelial tumors that typically develop in the sellar and suprasellar regions. Ectopic locations, such as the prepontine cistern, are exceedingly rare, especially in adults. Here, a 45-year-old female presented with a large cystic adamantinomatous craniopharyngioma (ACP) arising in the prepontine and suprasellar cisterns excluding any sellar involvement. Case Description: A 45-year-old female presented with a sudden-onset severe occipital headache and neck stiffness. The brain magnetic resonance (MR) revealed a well-defined, peripherally enhancing cystic lesion involving the suprasellar, interpeduncular, prepontine, and premedullary cisterns that compressed the ventral brainstem and displaced adjacent structures. On MR, the lesion demonstrated high T1 and T2 signal intensity, suggestive of proteinaceous content. Intraoperatively, the lesion was found in the anterior pontine cistern, extending from the foramen magnum to the floor of the third ventricle. At surgery, it contained yellow fluid containing cholesterol crystals. The histopathological examination confirmed an ACP. Conclusion: Large cystic craniopharyngiomas located in the prepontine cistern are extremely rare and may occur without sellar involvement and in the absence of endocrine dysfunction. MR and surgery confirmed the diagnosis of an ectopic craniopharyngioma in the prepontine cistern.