Large epidermal cyst involving the ischiorectal fossa: MR demonstration

Abstract A large subcutaneous mass was noted in the buttock of a 79-year-old man. Computed tomography (CT) and magnetic resonance imaging (MRI) showed a thinwalled cystic mass that involved the ischiorectal fossa. The content appeared hyperintense on T1-weighted images. T2-weighted images demonstrated a considerable amount of debris. At surgery an epidermal cyst with markedly keratinized squamous epithelium was found. It contained much keratin and cholesterin.