Fine needle aspiration cytology of primary epidermoid cyst of the brain.

The cytologic features of a primary epidermoid cyst of the brain diagnosed by intraoperative fine needle aspiration cytology are reported. The cytomorphologic findings included numerous anucleated squames, polarizable cholesterol crystals and a few squamous cells with keratohyaline granules. This case demonstrated the efficacy of using both the Diff-Quik and Papanicolaou stains in evaluation of cystic lesions of the brain. A discussion of the expected aspiration cytologic findings of other cystic cerebral lesions is also presented.