直腸の広範囲扁平腺腫の中央部に進行癌を伴った1例

A Case of Circumferential Adenomas of the Rectum with Coexisting Adenocarcinoma

　われわれは最近腸管全周にわたるfiat adenomaで組織学的には大部分がtubular adenomaであるが，中心部に癌巣を認め，癌巣に近づくにつれてadenomaがtubulo-villous，villous patternを呈した直腸腺腫の1例を経験した．本例について組織学的に検討を加え，腺腫と癌との関連を考察したので報告する．

症例

　患　者：中○そ○　69歳　女性

　家族歴・既往歴：特記すべきことなし

　初　診：1974年10月22日

　主　訴：下痢

　現病歴：1966年頃より便秘の傾向を認め時々下剤を使用し，また，便に血液が混在することもあったが痔核のためと思い放置していた．1972年頃より便柱は細くなり時々下痢が出現するようになった．1974年8月初旬より下痢が頻回となり，苦痛を覚えるようになった．便の性状は粘液が多量となったため同年10月5日近医にて注腸X線検査をうけ当科を紹介された．なお1972年より2年間に2kgの体重減少を認めた．

　A sixty-nine-year old woman, who had been suffering from constipation and diarrhea for the past eight years, was seen by a doctor in August 1974 for radiological examination. She was referred to our service in October 1974. Diagnosis was rectal cancer as confirmed by K-ray and proctoscopical examinations. The patient was submitted to Miles operation with regional lymph node dissection.

　Macroscopic observation of the lesion in the resected specimen was featured by an apparent advanced cancer in the midst of adenomas, which circumferentially extended 7 cm long along the rectum. Histologically adenocarcinoma muconodullare was observed in the midst of wide-spread adenomas.

　The circumferential adenoma mostly showed tubular pattern.

　Villous pattern was observed only in the adjacent area encircling the carcinoma in the center.

　This case is characterestic of having an extensive lesion of both cancer and adenomas together with the transional zonation from tubular adenoma through villous pattern to adenocarcinoma.

　The finding can hardly be explained by Collision Theory, in which adenomas and carcinoma co-existing in different portions of the rectum are said to fuse each other. This case may suggest the possibility of transformation of tubular adenoma to adenocarcinoma through villous pattern adenomas. Histochemically alkaline phosphatase activity was not detected in adenomas. However, it was positive in brush border of the cancer cells. Its significance remains to be studied in terms of intestinal metaplasia of the colon and rectum.