Two cases of inverted hyperplastic polyps of the colon and association with adenoma

Abstract

Here we report two cases of inverted hyperplastic polyps of the colon. The first patient showed three inverted hyperplastic polyps in the ascending colon, one of which was associated with adenoma. We immunostained this adenoma-associated polyp using anti-beta-catenin antibody and found accumulation of beta-catenin in the cytoplasm of the adenomatous lesion but not in the inverted hyperplastic polyp. This suggested an adenomatous polyposis coli (APC) mutation in the adenomatous region but not in the inverted hyperplastic polyp. The inverted hyperplastic polyp in the second patient was located at the caecum and was studied using magnifying colonoscopy. The polyp appeared to be flat and elevated with a depressed pit in the centre. After spraying with methylene blue dye, the pit pattern of the lesion was observed and small asteroid pits on the polyp were found, consistent with a hyperplastic gland pattern. From these results, we diagnosed inverted hyperplastic polyp of the colon by colonoscopy.

Invasive cancer arising in a colonic inverted hyperplastic polyp

“…Our case was unique and the histology detected the presence of not only an invasive, poorly differentiated carcinoma but also serrated adenomatous glands surrounded by hyperplastic glands. To date, three cases of IHP associated with adenoma have been reported [3]; however this is the first case report of both of invasive cancer and serrated adenoma arising in an IHP. Recently, serrated polyps have been histologically defined as polyps that demonstrate a serrated or "sawtoothed" appearance, and include hyperplastic polyps, serrated adenoma, and…”

Intramucosal Colon Cancer Developing in an Inverted Hyperplastic Polyp

“…Among them, three cases with an IHP were associated with adenomas,3 and one case with invasive cancer 4. For several years, hyperplastic polyps have been considered as non-neoplastic lesions without malignant potential.…”

“…IHPs of the colon are usually asymptomatic and are often detected incidentally on endoscopy 3. In some cases, the main clinical feature of IHPs of the colon is gastrointestinal bleeding or abdominal pain 2.…”

Clinicopathologic Features of Inverted Serrated Lesions of the Large Bowel

“…In the literature, there have been only 2 cases of ISLs that were examined by magnifying chromoendoscopy [24,26] . According to those prior descriptions, ISLs showed a star-like appearance under magnification.…”