Ultrastructure of a craniopharyngioma

A craniopharyngioma removed at surgery was examined by light and electron microscopy. The tumor consisted of both solid and cystic components. The cells lining the cysts, as well as those forming the solid masses, displayed desmosomes, tonofilaments, keratohyalin granules, and keratinization identical to those seen in the epidermis. Three distinct varieties of cysts were recognized in this tumor. The cysts occurring within the connective tissue stroma were lined by a row of cells with basement membrane covering. The cysts in the epithelial masses, on the other hand, were lined either by the slender processes of the stellate‐shaped cells with a reticulated surface coating, or by cells showing microvillous projections and frequent keratinization. Crystalline calcium deposits were present, predominantly in the keratinized zones. Furthermore, the tumor extended to the hypothalamic region evoking severe reactive gliosis with formation of Rosenthal fibers which consisted of masses of granular deposits within the astrocytic processes.