Adenomatous polyps in the gastrointestinal system rarely occur in childhood and are accompanied by syndromes such as Familial adenomatous polyposis, attenuated familial adenomatous polyposis, and MUTYH-associated polyposis, Gardner and Turcot syndrome, and also mismatch repair (MMR) gene defects. In this article, we want to present a rare patient who had adenomatous polyposis and in situ carcinoma and was detected biallelic MMR gene defect.
A 16-year-old female patient admitted with painless rectal bleeding, chronic abdominal pain, and anorexia for 1 year. Her physical examination was notable for multiple cafe au lait spots. The colonoscopic and histopathologic examination revealed multiple adenomatous polyps that one of them contains low-high grade dysplasia and in situ carsinoma. Genetic analysis revealed a homozygous mutation in the PMS2 gene [c.1164delT (p.H388Qfs*10) (p.His388GInfsTer10)] and she was diagnosed with constitutional MMR gene defect syndrome. Polypectomy was performed 4 times in 2 years period. Then, the patient’s last colonoscopic examination revealed a large broad polyp in the rectum and multiple polyps in the other colon segments, and she underwent colectomy because of high risk of colorectal cancer.
Adenomatous polyps are very important in childhood because of rarity. In particular, the presence of cafe au lait spots and a history of malignancy detected in relatives at an early age must be considered for CMMRD.