Discussion
Alimentary tract duplications are spherical or tubular structures, one of the rare developmental anomalies that can occur anywhere in the intestinal tract from the tongue to the anal canal. Most of the duplications are found in the pediatric population and involve the small bowel. On the other hand, colonic duplication cysts represent 6.8% of gastrointestinal duplication cysts (6). The definition was proposed that it is covered by flat muscles, has a gastrointestinal mucosa on the inner surface, and is in close contact with the part of the gastrointestinal tract (1). However, there are some cases reported as gastrointestinal duplication even if all three conditions are not met. This case met all of the above three items.
The shape of the alimentary tract duplications is roughly classified into tubular and spherical. The colon as a whole has many tubular overlapping intestines, but the rectum has many spheres. In the rectum, it is said to occur frequently in the posterior wall.
The first symptoms of rectal duplication are often constipation and abdominal distension, probably because of the exclusion of the intestinal tract. In some cases, it escapes outside the anus(7, 8). Overlapping ureters, bladder malformations, fistulas with the urethral system, and pyuria may be present(7). There are also cases of multiple intestinal infections and bleeding. The epithelium of duplication cyst is usually the colonic mucosa (9), but in rare cases, ectopic gastric mucosa may be present. It causes ulcers and bleeding.
Surgical resection is the main treatment of choice(5). If the main intestine and the wall of the duplication tract share a muscular layer, a method of removing only the mucosa may be used. There is also a report that malignancy is observed when asymptomatic progresses despite the presence of ectopic gastric mucosa (10). We chose robot-assisted rectal resection as the surgical procedure.