Ⅱc型早期大腸癌の1例

Depressed (Ⅱc) Type Early Cancer of the Transverse Colon, Report of a Case

要旨　大腸早期癌には隆起性病変が多く陥凹性病変（Ⅱc）は非常にまれである．Ⅱc型早期癌が少ないのは大腸癌の組織発生，進展に起因しているのかもしれないが，大腸癌の組織発生を知るうえで陥凹性病変は1つの手掛かりを与えてくれるかもしれない．患者は72歳の男性で心窩部痛の精査中に偶然発見された病変である．横行結腸の約1cm程度の陥凹性病変で，注腸造影および内視鏡的には隆起を伴わない陥凹のみの病変であり，Ⅱc型早期癌と診断された．組織学的には粘膜下にわずかに浸潤した高分化腺癌であり，腺腫の共存は認めずdenovo癌と考えられた．

　Early colorectal cancers have been reported with increasing frequency, but depressed types of these have been rarely reported.

　A 72-year-old man had barium enema and colonofiberscopy because of upper quadrant abdominal pain. Barium enema showed an irregular barium deposit in the transverse colon, while colonofiberscopy revealed a depressed type lesion of about 1 cm in diameter. Right hemicolectomy was performed with lymph node dissection. The lesion was so-called Ⅱc type early cancer. Regional lymph nodes were free from metastasis. Microscopically, the lesion was well differentiated adenocarcinoma with slight submucosal invasion. There was no adjacent adenoma around the cancer. It was considered that the early cancer could arise “de novo” in the normal colonic mucosa.

　Double contrast barium enema and colonofiberscopy should be done paying extreme attention to the potential presence of this type of early cancer.