Craniopharyngioma, light micrograph. Craniopharyngioma is a燱HO Grade 1 epithelial tumour爑sually seen in the爏ellar/suprasellar region. It arises most likely from the爎emnants of Rathke's pouch. Some cases may have their origin in爉isplaced odontogenic rests along pituitary stalk. Grossly, they are often爏olid and cystic with areas of calcification. Craniopharyngiomas are subdivided into two types based on morphologic features: 1) Adamantinomatous (90% of cases) seen mostly in children and 2) Papillary (10% of cases) seen mostly in adults. This image shows most of the爇ey diagnostic features of an adamantinomatous craniopharyngioma: a) sheets of爏quamous epithelial cells with peripheral palisading?best seen along the bottom of the image); b) a loose meshwork of epithelial cells called the爏tellate reticulum; c) nodules of anucleated squames (ghost cells) with brightly eosinophilic cytoplasm termed爓et keratin. Wet keratin is considered diagnostic even in the absence of viable epithelium.