A 63-year-old man was referred to our 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. Colonoscopy revealed
diverticulosis in the sigmoid colon, and a 2-cm-diameter, hard mass within multiple
diverticula. The mass was surrounded by normal mucosa, mimicking a submucosal tumor,
and an apparently depressed area was identified at the top of the lesion ([Fig. 1]). Because chromoendoscopy using indigo carmine dye clearly showed the margin of
the depressed area, the lesion was suspected to be a depressed-type neoplasm, and
magnifying colonoscopy with crystal-violet staining showed type IIIL and type IIIs
Kudo pit patterns ([Fig. 2]), mainly corresponding to an intramucosal neoplasm; a biopsy sample from the depressed
area showed features characteristic of adenoma. The lesion was finally diagnosed as
a depressed-type intramucosal neoplasm arising from the diverticulum. 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 histopathological evaluation of the resected specimen revealed an intramucosal
depressed-type adenocarcinoma, 18 mm × 15 mm in size, accompanied by numerous diverticula
([Fig. 3]). No evidence of lymph node metastasis was found, and the patient recovered uneventfully.
Fig. 1 A depressed lesion surrounded by normal mucosa in the sigmoid colon, visualized by
spraying with indigo carmine dye.
Fig. 2 Magnifying colonoscopy with crystal-violet staining showed type IIIL and type IIIs
Kudo pit patterns in the lesion.
Fig. 3 Histopathological views of the resected specimen after staining with hematoxylin and
eosin at original magnification × 10 (a) and at original magnification × 200 (b), showing a depressed-type intramucosal adenocarcinoma with numerous diverticula.
Although it is still unclear whether diverticular disease is a risk factor for colon
cancer, several investigators have described colon cancers associated with diverticulosis
or within a diverticulum [1]
[2]
[3]
[4]
[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. Moreover, to our knowledge, this is the first report of a depressed-type
colon cancer occurring with diverticulosis. Although in this case we were unable to
confirm that the cancer had arisen within a diverticulum, we were also unable to explain
the unusual appearance of this lesion without reference to the influence of the coexisting
diverticulosis.
Endoscopy_UCTN_Code_CCL_1AD_2AB
