遺伝性素因の関与が示唆された潰瘍性大腸炎 合併多発性早期大腸癌の1例

Multiple Early Colorectal Cancers (Hereditary Non-polyposis Colorectal Cancer) and Ulcerative Colitis, Report of a Case

要旨　症例は42歳，女性，全大腸炎型の潰瘍性大腸炎患者で，発症11年目にS状結腸と直腸に4つの扁平な隆起性病変を認め，生検にてdysplasiaないし腺癌の組織像が得られたため，大腸亜全摘術を施行．切除大腸の全割標本では隆起性病変に一致して計4個の早期癌（高分化腺癌；m癌2個，sm癌2個）とその周囲にdysplasiaを認めた．一方，本例は多臓器腺癌（胃癌，乳癌）の既往と消化管腺癌の家族内集積（母親；直腸癌，弟；胃癌）を認め，いわゆる遺伝性非ポリポーシス大腸癌の家系であった．本例は潰瘍性大腸炎合併早期大腸癌としては典型例と考えられたが，大腸癌の若年発生，多発性の要因として遺伝性素因の関与も示唆された．

　A 42-year-old female with ulcerative colitis throughout her entire colon developed multiple early colorectal cancers during the 11-year follow-up period. Barium enema and colonoscopy showed four flatly elevated lesions in the sigmoid colon and the rectum. Subtotal colectomy and mucosal proctectomy were carried out because the biopsy specimens taken from these lesions revealed severe dysplasia or adenocarcinoma.

　Histological examination of the resected specimen revealed that the four elevated lesions were well differentiated adenocarcinomas ; Two lesions were restricted to the submucosa, and the remaining two to the mucosa. It was speculated that the four carcinomatous lesions may have arisen from dysplasia because of the existence of many dysplastic lesions in the surrounding mucosa.

　The patient also had a previous history of gastric and breast cancers. In addition, two of her first degree relative had been diagnosed as having gastric or rectal cancers. Considering these histories, she was diagnosed as a member of a hereditary non-polyposis colorectal cancer (HNPCC) family.

　As far as we can ascertain, our patient is the first reported case of ulcerative colitis with colorectal cancer, which was accompanied by HNPCC. Both the genetic factor and the long-term course of ulcerative colitis were considered to be related to the early onset and the multiplicity of colorectal cancers in the patient.