Lesions of the Lower Intestinal Tract
Moderators: Dr. Henry Appelman and Dr. Joel K. Greenson
Case 12 -
Depressed type adenoma (low-grade dysplasia)
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
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
The depressed type adenomas comprise 0.2 to 3.1% of all neoplastic lesions found in endoscopic
and 8.4% of adenomas appeared in the surgically resected
specimens.  Usually they are small in size that more than 95% of all were reported to be less
than 5 mm in diameter.
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.
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- 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.