A 63-year-old woman presented with a complaint of left buttock mass that had rapidly increased in size after a recent trauma. The patient was otherwise asymptomatic, denying any pain or constitutional symptoms. On physical exam, a well-defined, firm, freely mobile 20-cm mass with intact, non-erythematous overlying skin was palpated in the medial-lower quadrant of the left buttock, contiguous to the left perineal region. On digital rectal examination, the mass was palpable on left posterior aspect of the rectal wall, with smooth and intact overlying mucosa.