Case 12 -

Depressed type adenoma (low-grade dysplasia) Yoichi Ajioka

Case History: 54-year-old male, complaining of anal prolapse, was found rectal carcinoma and surgical operation was done. The lesion, measuring 2x1mm in the sigmoid colon, was found by pathological examination of the resected specimen. Commentary Histopathology Similar to Case 11, the depression is formed by a reduction in the thickness of the mucosa which is composed of neoplastic glands with simple tubular structure. Tumor is confined to the mucosa and shows low-grade cytology; basally oriented spindle shaped nuclei with little or no pseudostratification and goblet cell differentiation. Case 12 - Slide 1 Click to view with ImageScope Click to view with a Web-Based Viewer Discussion The depressed type adenomas comprise 0.2 to 3.1% of all neoplastic lesions found in endoscopic examinations, [4, 5, 6, 7, 8] and 8.4% of adenomas appeared in the surgically resected specimens. [1] Usually they are small in size that more than 95% of all were reported to be less than 5 mm in diameter. [1, 2] The natural history of depressed type adenomas is unknown. They probably have the potential to progress to the depressed type carcinoma, while they can develop into ordinary polypoid adenomas. [1, 3] References Kubota O, Kino I, Kimura T et al. Nonpolypoid adenomas and adenocarcinomas found in backgroud mucosa of surgically resected colons. Cancer 1996; 77: 621-626. Tsuruta O, Toyonaga A, Shigematu T et al. Endoscopic diagnosis and treatment for minute lesions of the colon (in Japanese with English abstract). I to Cho (Stomach Intest) 1995; 30: 1499-1506. Suzuki Y, Honma T, Kobayashi M et al. A case report of minute colonic adenoma of which macroscopic appearance has changed from superficial-depressed type to superficial-elevated type (in Japanese with English abstract). Gastroenterol Enodsc 2000; 42: 1090-1095. Jaramillo E, Watanabe M, Slezak P et al. Flat neoplastic lesions of the colon and rectum detected by high-resolution video endoscopy and chromoscopy. Gastrointest Endosc 1995; 43: 114-122. Fujii T, Rembacken BJ, Dixon MF et al. Flat adenomas in the United Kingdom: are treatable cancers being missed? Endoscopy 1998; 30: 437-443. Rembacken BJ, Fujii T, Cairns A et al. Flat and depressed colonic neoplasms: a prospective study of 1000 colonoscopies in the UK. Lancet 2000; 355: 1211-1214. Kiesslich R, von Bergh M, Hahn MG et al. Chromoendoscopy with indigocarmine improves the detection of adenomatous and nonadenomatous lesions in the colon. Endoscopy 2001; 33: 1001-1006. Tsuda S, Vercess B, Toth E et al. Flat and depressed colorectal tumors in a southern Swedish population: a prospective chromoendoscopic and histopathological study. Gut 2002; 51: 550-555.