Adenocarcinoma arising within a colonic diverticulum.

A case of cancer arising in a diverticulum of the ascending colon in a 67-year-old male is reported. The 1.5 x 1.0 cm well-differentiated adenocarcinoma protruded from the base of the inverted mucosa of the diverticulum. The surrounding flat colonic mucosa was not involved by the cancerous process. Focal stromal invasion was seen in the subserosal tissue, without association of lymph nodal involvement. This is the third reported case of adenocarcinoma arising in the colonic diverticulum.