Malignant transformation of intracranial epidermoid cyst

Intracranial epidermoid cysts (ECs) are rare, histologically benign, slow-growing, congenital neoplasms of central nervous system that may arise from retained ectodermal implants. Malignant transformation of an EC to squamous-cell carcinoma is rare; only 13 cases have been reported. We present the case of a 42-year-old woman presenting with left hemiparesis 18 months after performing partial resection of an epidermoid cyst of right middle and posterior fossa, whose pathological report revealed to be a malignant transformation of previous epidermoid tumor. Additionally, we performed pertinent literature review.