An elusive cause of perianal pain in a patient with Hirschsprung's disease.

A 23-year-old woman presented to the outpatients department with symptoms of acute onset perianal pain of 2 weeks' duration and constipation. She was a known case of Hirschsprung's disease and was operated on in infancy. Rectal examination ruled out acute fissure or perianal sepsis, and subsequent colonoscopy was normal. Because of persistent symptoms, she was evaluated further by imaging which revealed a presacral lesion closely abutting the nerve roots, suggesting the possibility of a nerve sheath tumour. The tumour was excised by the perineal route, and surprisingly the histopathology report revealed an epidermoid (sebaceous) cyst. Presacral tumours are very rare lesions which most colorectal surgeons never come across in their careers. Tumours range from indolent, to benign, to more aggressive malignant lesions. Usually the symptoms are non-specific and surgical excision remains the best treatment. Multidisciplinary team work is needed for most of these cases. 2016 BMJ Publishing Group Ltd.