Perforated caecal duplication cyst presenting as an appendicular abscess.

A duplication cyst of the caecum is a very rare congenital malformation, representing 0.4% of all gastrointestinal duplications. We present a case of cystic duplication of the caecum in a 12-year-old child who presented with a right iliac fossa mass and peritonitis. An ischaemic, perforated caecal duplication cyst was found on emergency laparotomy, mandating a right hemicolectomy.