Abstract
Two cases of malignant villous tumor (carcinoma) were encountered among a total of 163 cases of colorectal cancer which underwent resection at our hospital in the past nine years. Case 1 was a case of villous cancer which developed in the transverse colon. Case 2 had three types of concurrently developed cancer consisting of cancer in a villous adenoma in the ascending colon, a localized Borrmann 2 type adenocarcinoma in the cecum and ha cancer in the sigma. It is widely known that a villous tumor prefers a site locating within 25cm from the anus and that it is rather rare to develop in the oral site of the colon. The histopathological pictures were demonstrably different between the two cases. Case 1 was a malignant villous tumor infiltrating into the tunica musclaris with a pronounced property of low grade malignancy with slow growth in the depth. However, case 2 featured a strong property characterized by cancerous transformation of a villous adenoma. Interesting finding of histopathological pictures as a class of villous tumor have prompted us to present the observations and certain comments from the literature. Furthermore, case 2, with concurrent multiple cancers including cancer in a villous adenoma, was thought to be a relative rarity in that only two cases had been reported in Japan.
