Radiology for the surgeon. Soft-tissue case 59. Giant epidermal cyst of the ischiorectal fossa.

A old previously healthy woman presented to our outpatient clinic with a chief complaint of a huge mass in the left buttock that had gradually increased in size during the previous 7 years. The mass was painless, but it caused great difficulty in sitting and walking. She did not complain about dyspareunia or any problem with defecation. Physical examination revealed a 10-cm cystic mass in the left buttock region (Fig. 1) that was nontender. Rigid sigmoidoscopy did not show any rectal lesion. The patient underwent magnetic resonance imaging of the pelvis. The representative images (Fig. 2, Fig. 3) are shown. What is the likely diagnosis? Continuing Medical Education Formation médicale continue