Serrated Lesions of the Appendix A Morphologic and Immunohistochemical Appraisal
ABSTRACT We performed a histologic and immunohistochemical assessment of 53 noninvasive appendiceal epithelial proliferations, appropriating terminology and using markers shown useful in differentiating serrated colorectal polyps. These were classified as hyperplastic polyp (HP), sessile serrated adenoma (SSA), mixed serrated and adenomatous lesion (MSAL), mucinous cystadenoma (MCA), or conventional adenoma (CAD). Immunohistochemical analysis for cytokeratin (CK) 20, Ki-67, MUC6, and beta-catenin was performed. Diagnoses were as follows: HP, 6; SSA, 12; HP vs SSA, 3; MSAL, 16; MCA, 14; and CAD, 2. All HPs showed expanded (beyond surface) CK20 and expanded or normal (base) Ki-67; 1 was MUC6+. Most SSAs and MSALs were CK20-expanded or expanded with random expression in deep crypts (Ex/I) and Ki-67-expanded, Ex/I (expanded with asymmetry), or normal. All SSAs and 8 of 16 MSALs were MUC6+. CADs were CK20-Ex/I, Ki-67-Ex, and MUC6-; 1 showed nuclear beta-catenin expression. Serrated appendiceal lesions can be categorized using colorectal terminology. MUC6 is associated with SSA morphologic features. Similar immunohistochemical patterns in SSA and MSAL suggest a link between these lesions.
- American Journal of Clinical Pathology 04/2010; 133(4):529-32. DOI:10.1309/AJCPUPMRP1RTDSU2 · 3.01 Impact Factor
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ABSTRACT: Background/Aims: The aim of this study is, therefore, to classify appendiceal serrated polyps in a large case series with respect to the recent World Health Organization classification using diagnostic criteria provided for colorectal serrated polyps. Materials and Methods: A total of 960 appendix specimens diagnosed between 2005 and 2010 were reviewed retrospectively, and cases presenting with a polyp with serrated morphology were classified with reference to the recent World Health Organization criteria. Histologic criteria comprised architectural features of the crypts, including serration, branching, basal dilatation, inverted T-or L-shaped crypts together with cytologic features comprising a mucin pattern, dysplasia, in terms of pseudostratification and nuclear atypia, mitoses in the upper crypts, and cytoplasmic eosinophilia. Results: A total of 71 cases (7.39%) were diagnosed as serrated polyps, including 36 (50.7%) hyperplastic polyps, 33 (46.48%) sessile serrated adenoma/polyps, and 2 (2.81%) traditional serrated adenomas. There were 32 males and 39 females with an age range of 2 to 82 years. Histology revealed that the majority of both hyperplastic polyps (63.9%) and sessile serrated adenomas/polyps (74.3%) involved the entire appendiceal circumference. Basal dilatation (94.3%), basal serration (94.3%), T-/L-shaped crypts (94.3%), and ectopic crypts (68.6%) were significantly more commonly observed in sessile serrated adenomas/polyps compared to hyperplastic polyps. Dysplasia was observed in 31.4% of sessile serrated adenomas/polyps, while hyperplastic polyps did not show dysplasia. Conclusion: The results of the present study suggest that appendiceal serrated polyps, despite bearing many similarities with their colorectal counterparts, may have some special features due to the anatomic uniqueness of the organ itself and also the polyps arising from its mucosal lining.The Turkish journal of gastroenterology: the official journal of Turkish Society of Gastroenterology 02/2014; 25(1):29-34. DOI:10.5152/tjg.2014.4056 · 0.47 Impact Factor
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ABSTRACT: Appendiceal serrated polyps often morphologically resemble their colorectal counterparts and most pathologists employ colorectal diagnostic terminology when evaluating appendiceal serrated lesions. We analyzed 132 appendiceal lesions for mutations in the RAS/RAF/MAPK pathway in an attempt to (1) determine the frequency of these mutations in appendiceal serrated lesions and (2) correlate the histopathologic features with molecular alterations. The study group of appendiceal serrated lesions (n = 46) was divided into a non-dysplastic group (28/46, subclassified as 7 hyperplastic polyps and 21 sessile serrated adenoma/polyps (SSA/P) using colorectal diagnostic terminology) and dysplastic group (18/46, subclassified as 9 SSA/Ps with cytological dysplasia, 7 traditional serrated adenomas, and 2 adenomas with prominent serrations). Appendiceal non-serrated dysplastic lesions (n = 86) comprised the control group. Of the 123 lesions analyzed, KRAS mutations were identified in 64 (52%) appendiceal lesions. No significant difference in the presence of KRAS mutations were identified between serrated non-dysplastic lesions (13/25, 52%), serrated dysplastic lesions (7/14, 50%) and the control group of non-serrated dysplastic lesions (44/84, 52%) (P = 1.0). Importantly, KRAS mutations were identified in lesions that were histologically identical to colorectal hyperplastic polyps (2/6, 33%), SSA/Ps (11/19, 58%), and SSA/Ps with cytological dysplasia (4/7, 57%). Of the 126 lesions tested, BRAF V600E mutations were identified in only 5 (4%) appendiceal lesions. Our results indicate that serrated lesions of the appendix often harbor KRAS mutations rather than BRAF mutations and suggest that the serrated pathway in the appendix is likely different than in the colon and rectum.Human pathology 02/2014; 45(2):227-35. DOI:10.1016/j.humpath.2013.10.021 · 2.81 Impact Factor