Ectopic cerebellum presenting as a suprasellar mass in infancy: Implications for cerebellar development

A 4-month-old infant with a history of nasopharyngeal teratoma developed pr ogressive optic neuropathy. Neuroimaging studies demonstrated a solid, isoi ntense, suprasellar mass impinging on optic nerves and chiasm superiorly. T he mass was subtotally resected. No attachment of the mass to brain stem or cerebellar structures was noted. Histological examination identified the t issue as developing cerebellum. The cytoarchitecture and cellular constitue nts of the cerebellar tissue were only slightly distorted. All cerebellar c ortical constituents were arranged anatomically, and an external granular c ell layer was present superficially. The latter was actively proliferating and appropriately cellular for the infant's age. The clinical presentation of ectopic cerebellum as a suprasellar mass in an infant is highly unusual. Moreover, this example illustrates the ability of cerebellar tissue to mat ure appropriately in a site distant from the posterior fossa, removed from ascending and descending afferent projections. Intrinsic signaling mechanis ms appear sufficient to direct histogenesis in developing cerebellar cortex .