Lynch症候群と原発性小腸癌

Lynch Syndrome and Primary Small Bowel Cancer

要旨●Lynch症候群は主にミスマッチ修復遺伝子の生殖細胞系列変異を原因とする常染色体優性遺伝性疾患であり，大腸癌をはじめとする種々の固形腫瘍が好発する．小腸癌もLynch症候群関連癌に含まれるが，小腸スクリーニングの時期や方法は定まっていない．自験例を含めLynch症候群に合併した小腸癌本邦報告例14例16病変について検討したところ，貧血や腹痛などの症状を訴え，進行癌として発見された例が多く，MSH2変異を認める場合は特に小腸癌合併に注意を要すると考えられた．自験Lynch症候群関連小腸癌の1例は40歳代，男性で，貧血を契機に診断された回腸進行癌術後4年目のカプセル小腸内視鏡にて空腸腸型腺腫を認め，バルーン内視鏡下で切除しえた．小腸癌の早期発見につながる可能性のある症例と考え報告する．

　Lynch syndrome is a disease in which germline mutations in mismatch repair genes predispose patients to the development of various tumors. Small bowel cancer is one of the Lynch syndrome-related cancers ; however, the timing and methods of small intestine screening have not yet been established. We examined 16 lesions in 14 cases of Japanese small bowel cancer associated with Lynch syndrome, including our own case, and found that many of the lesions were identified as advanced cancer with symptoms such as anemia and abdominal pain and that the presence of the MSH2 mutation should be considered as a concern for small bowel cancer complications. Our case of Lynch syndrome-related small intestinal cancer was that of a 40s man. Four years after surgery for advanced cancer of the ileum, which was diagnosed due to anemia, a jejunal intestinal adenoma was found via capsule small bowel endoscopy and successfully resected via balloon-assisted endoscopy. We herein report this case for highlighting the methods and importance of early detection of small intestinal cancer.