肺の癌性リンパ管症を惹起した微小結腸癌の1剖検例

Small Colon Carcinoma Developing Pulmonary Lymphangitic Carcinomatosis, Report of an Autopsy Case

要旨　一般的には，大腸癌は癌巣の大きさが小さいものは早期癌が多く，原発巣が大きくなると進行癌が多いとされている．最近，肺の癌性リンパ管症にて急性の経過で死亡し，剖検により，S状結腸に小さい原発巣が発見された症例を経験した．症例は55歳，男性で，咳嗽，呼吸困難で入院した．胸写では全肺野に粒状，索状影がみられた．肺生検により癌が認められ，肺の癌性リンパ管症と診断された．入院後，約1か月で呼吸不全にて死亡した．剖検にてS状結腸に0.8cm大の山田Ⅱ型の隆起性病変が認められ，組織学的には低分化腺癌で，著明なリンパ管浸潤がみられた．後腹膜，縦隔，肺門リンパ節に転移を認めた．

　A 55 year-old man admitted because of cough and dyspnea. Chest roentgenogram showed diffuse reticulonodular shadows throughout both lungs (Fig. 1). TBLB revealed carcinoma (Fig. 2) and a diagnosis of lymphangitic carcinomatosis was made. He expired because of respiratory failure due to progression of the pulmonary lesion.

　At autopsy, a small sessile polypoid lesion, measuring 8 mm at the largest diameter, was noticed (Fig. 4). Histological examination revealed poorly differentiated adenocarcinoma with marked lymphangitic invasions (Figs. 5 and 6). Metastasis was evident in retroperitoneal, paraaortic, mediastinal and pulmonary hilar lymphnodes. No metastasis was found in the liver.

　In general, colon carcinomas invade the deeper layers of the intestinal wall in proportion to their sizes. It is very uncommon that such a small colon carcinoma should develop widespread metastasis including pulmonary lymphangitic carcinomatosis. Poorly differentiated adenocarcinoma and massive lymphatic invasions were thought to be risk factors for spreading colon carcinoma in this case.