Colorectal polyps with extensive absorptive enterocyte differentiation: histologically distinct variant of hyperplastic polyps.

BACKGROUND: The histologic classification of colorectal polyps is well established. However, practicing pathologists may still occasionally encounter colorectal polyps that are difficult to classify. We studied 6 colorectal polyps that showed uncommon histologic features that have not been described in the English language literature. MATERIALS AND METHODS: The polyps were studied using standard hematoxylin-eosin stain, mucin histochemistry, and electron microscopy. RESULTS: The 6 polyps we studied showed extensive papillary and villous structures with alternating villi and crypts. The villi were lined by well-differentiated absorptive cells, whereas the crypts were lined by immature glandular cells, thus mimicking the histology of the small intestinal mucosa. CONCLUSIONS: These polyps appear to represent a variant of the hyperplastic polyp, in as much as cellular maturation (immature glandular cells differentiate into the mature surface absorptive cells) is the essential feature distinguishing hyperplastic polyps from adenomas.

Lymphoepithelial cyst of the pancreas with sebaceous differentiation.

Lymphoepithelial cysts of the pancreas are rare cystic lesions that histologically resemble branchial cleft cysts. In this article, we report a case of lymphoepithelial cyst with sebaceous differentiation. Lymphoepithelial cysts may present clinically or may be incidental findings, and they should be considered in the differential diagnosis of cystic lesions of the pancreas. The histogenesis of lymphoepithelial cyst is briefly discussed.