Duplication of the vermiform appendix in an adult patient.

Duplication of the appendix is extremely rare. A 69-year-old woman was admitted with a 2-day history of right lower quadrant abdominal pain. Physical examination was consistent with acute appendicitis. Ultrasonography and colonoscopy gave a clinical impression of an inflammatory appendiceal mucocoele. Operative findings were an enlarged and inflamed appendix with distal cystic changes. Laparoscopic wedge resection of the caecum was performed. A tubular structure with a true lumen was found in the appendix. Haematoxylin and eosin staining and trichrome staining showed both structures had a true mucosa and a muscular layer. The duplication in this case does not belong to any of the previously described types of duplication.