Depressed-type colon cancer in a patient with diverticulosis.

hospital with a history of hematochezia. He had no previous history of abdominal complaints or of abdominal surgery. Physical examination and laboratory parameters showed no abnormalities. Co− lonoscopy revealed diverticulosis in the sigmoid colon, and a 2−cm−diameter, hard mass within multiple diverticula. The mass was surrounded by normal mu− cosa, mimicking a submucosal tumor, and an apparently depressed area was identi− fied at the top of the lesion (l" Fig. 1). Be− cause chromoendoscopy using indigo car− mine dye clearly showed the margin of the depressed area, the lesion was sus− pected to be a depressed−type neoplasm, and magnifying colonoscopy with crys− tal−violet staining showed type IIIL and type IIIs Kudo pit patterns (l" Fig. 2), mainly corresponding to an intramucosal neoplasm; a biopsy sample from the de− pressed area showed features character− istic of adenoma. The lesion was finally diagnosed as a depressed−type intramu− cosal neoplasm arising from the diverti− culum. Although these lesions are usually treated endoscopically, the coexistence of diverticulosis was thought to pose a high risk of perforation. A sigmoidectomy was therefore performed, and histopathologi− cal evaluation of the resected specimen revealed an intramucosal depressed−type adenocarcinoma, 18 mm ” 15 mm in size, accompanied by numerous diverticula (l" Fig. 3). No evidence of lymph node metastasis was found, and the patient re− covered uneventfully. Although it is still unclear whether diver− ticular disease is a risk factor for colon cancer, several investigators have de− scribed colon cancers associated with diverticulosis or within a diverticulum [1 ±5]. Because diverticulosis can mask the symptoms of cancer and can also make colonoscopic observation difficult, intramucosal cancer in association with diverticulosis is rarely reported. More− over, to our knowledge, this is the first re− port of a depressed−type colon cancer oc− curring with diverticulosis. Although in this case we were unable to confirm that the cancer had arisen within a diverticu− lum, we were also unable to explain the unusual appearance of this lesion with− out reference to the influence of the coex− isting diverticulosis.