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65-year-old man with bi-temporal superior quandrantanopsia. Neuroimaging shows a sellar mass.
Pituicytoma is a rare tumour of the neurohypophysis and/or pituitary stalk occurring mainly in adults. It is cured by complete surgical resection and is classified as WHO grade I. Pituicytoma is thought to arise from pituicytes, modified glial cells in the neurohypophysis. Clinically, pituicytoma is hard to distinguish from a non-functioning pituitary adenoma. Microscopically, the tumour is composed of compact fascicles or storiform arrangements of bipolar spindle cells with oval to elongated nuclei. There is little to no nuclear atypia and mitoses are rare, if present. Immunohistochemistry shows expression of vimentin, S100, and TTF1 (involved in the development of the diencephalon; see Related Content); GFAP is variable.