Prolapsed giant sigmoid lipoma: a rare cause of adult ischaemic intussusception.

Intussusception is a rare cause of obstruction in adults and has a variable, non-specific presentation. Adult intussusception is usually associated with an underlying organic pathology, such as a benign or malignant tumour which acts as the lead point. Prolapse of the lead-point mass through the anal canal is an extremely rare presentation with very few reported cases in the literature. We describe a case of a 67-year-old man who presented with rectal prolapse of a large soft tissue mass. CT of the abdomen and barium enema revealed partial intussusception of an upper sigmoid lipomatous polyp. Examination under anaesthesia was performed and the prolapse reduced. A laparoscopic sigmoid colectomy was planned. The patient subsequently re-presented clinically unwell with a recurrent necrotic prolapsing mass. Laparotomy and sigmoid colectomy was performed and the patient recovered fully. The resected mass was a 7×4.5×4.0 cm necrotic sigmoid lipoma.