大腸癌を合併しない比較的高齢な家族性大腸腺腫症の1例

Familial Adenomatous Polyposis without Cancer Occurring in Elderly Women, Report of a Case

要旨　症例は67歳，女性．検診目的で大腸造影検査を受け，ポリープの多発を指摘され，大腸内視鏡検査にて大腸ポリポーシスと診断された．遺伝子診断にて，APC遺伝子のexon15，codon1992の部位にCのdeletionを認め，この結果，この部位の配列はCCCCCTからCCCCTGとなり，codon2043にstop codonを生じるframe shift mutationを認め，genotypeからはattenuated familial adenomatous polyposis（AFAP）と診断された．右半結腸切除術および直腸S状部切除術を施行した．切除標本には，多発するポリープを確認．また病理診断では，ポリープはいずれも腺腫であり，癌の発生を認めなかった．AFAPと診断された場合には，APC遺伝子の変異の場所により表現型も異なり，予防的全大腸切除が必要とならないケースがあることが示された．

　A 67-year-old female patient was found, by both barium enema and colonoscopic examination, to have multiple polyps in the colon. Genetic analysis was carried out, revealing deletion of cytosine at codon 1992 in exon 15 of APC gene, causing frame shift mutation. On genotype, it was thought to be attenuated familial adenomatous polyposis.

　Right hemicolectomy and rectosigmoidectomy were performed under the diagnosis of attenuated familial adenomatous polyposis (AFAP). Histopathological findings showed no cancerous lesion, suggesting tubular～tubulovillous adenoma with mild～moderate atypia.

　AFAP is a clinical phenotype which has various manifestations. This indicates that prophylactic surgery is not always an appropriate treatment option in AFAP cases.

　1) Department of Surgery, Hoshi General Hospital, Koriyama, Japan

　2) Department of Surgery, Social Insurance Nihonmatsu Hospital, Nihonmatsu, Japan