Microscopic description and IHC:
The mass is well circumscribed, composed of fibrovascular stroma surrounded by well differentiated squamous epithelium with pseudopapillary formation. No obvious areas of stellate reticulum, "wet" keratin, calcification, or xanthogranulomatous inflammation are present.
Discussion:
The sellar/supersellar location of the mass gives away the key clue to the diagnosis of craniopharyngioma. Differential diagnosis in patient of his age and radiographic appearance includes chordoid glioma, ependymoma, and metastatic carcinoma.
Craniopharyngiomas have two peaks of occurrence, before the 3rd decade of and in the fifth decade of life. They are rare tumors occur in the sellar region near third ventricle developed from nests of epithelium derived from Rathke's pouch. They are slow growing tumors with rare malignancy.
The entity is divided into the adamantinomatous/pediatric type, papillary/adult type, or mixed. The prognosis of each subtype are approximately the same. The pediatric variant is more often calcified, with peripheral palisaded nuclei, ghost cells, loose central cells (stellate reticulum), abundant keratin with “wet” appearance, and can undergo xanthogranulomatous reaction or cystic degeneration. The adult variant shows papillary formation with nonkeratinizing stratified squamous epithelium. There are usually no stellate reticulum, “wet” keratin, nor xanthogranulomatous reactions.
References:
Rushing EJ, Giangasper F, Paulus W, Burger PC. Craniopharyngioma. In Louis DN, Ohgaki H, Wiestler OD, Cavenee WK (eds): WHO classification of tumours of the central nervous system. Lyon, 2007, IARC Press, pp. 238-240.