Craniopharyngiomas are benign (WHO Grade I) intracranial tumours that arise in the sellar/suprasellar region. Their exact origin is not known but they are thought to be derived from embryonic remnants of Rathke’s pouch epithelium in the pituitary gland. There are two main pathological types of craniopharyngioma: adamantinomatous and papillary.

The adamantinomatous type (as shown in this case) is the most common type and it typically occurs in children. Grossly, they present as lobulated cystic lesions filled with dark “motor oil” fluid with frequent calcifications. They often have irregular borders with finger-like extensions into the surrounding brain parenchyma, making the possibility of complete surgical resection difficult. Histologically, they resemble ameloblastoma of the jaw and the adamantinoma of the bone. The cysts are lined by ribbons of complex squamous epithelium with peripheral palisading, a middle stellate reticulum (resembling the enamel pulp of developing teeth) and a top keratin producing layer. Admixed with the epithelial ribbons, there are multiple “wet keratin” nodules composed of ghost-like anucleate cells. Scattered granulomatous inflammation, giant cells and cholesterol clefts can also be seen. The interface with the brain parenchyma shows marked gliosis and Rosenthal fiber formation.