[641] Prolapse-Type Changes Can Lead to Overdiagnosis of Sessile Serrated Adenomas of the Rectum: A Histopathologic Study of 75 Rectal Polyps.

Cheng Huang, Wendy L Frankel, Theodore Doukides, Weiqiang Zhao, Martha M Yearsley. The Ohio State University, Columbus

Background: Serrated polyps of the colorectum include hyperplastic polyp (HP), sessile serrated adenoma (SSA) and traditional serrated adenoma (TSA). The differentiation is clinically important as SSA and TSA have higher risk to progress to cancer than HP. We investigated whether architectural distortion due to prolapse-type changes in the rectum could make the distinction between SSA and HP challenging.
Design: 63 cases were identified by searching the archives of an academic and community pathology practice for “sessile serrated adenoma“, “hyperplastic polyps with features of sessile serrated adenoma” and “serrated polyp” from January 2006 to July 2010. The cases were reviewed by two GI pathologists and re-classified based on the classically described histologic features of these polyp types. Polyp size was noted.
Results: 63 cases contained one or more polyps for a total of 75 polyps. Initial diagnosis included 21 SSA, 9 HP, 35 HP with features of SSA, 4 tubular adenomas with features of serrated polyp, 3 SP with features of SSA, 2 tubular adenomas arising in the background of sessile serrated adenoma, and 1 tubular adenoma. Polyp size ranged from 2-20 mm. The polyps were reclassified into the following categories: SSA (7), HP (22), HP with features of rectal prolapse (24), serrated polyp favor inflammatory polyps (12), SSA with dysplasia (2), Tubular adenomas (7), and rectal prolapse (1). Many of those cases initially classified as SSA (or having features of SSA) on review were felt to represent HP and/or prolapse change.
Conclusions: Prolapse-type architectural changes such as crypt distortion and exaggerated serrated changes are pitfalls for the overdiagnosis of sessile serrated adenomas of the rectum. When prolapse-type features are identified, cyto-architectural criteria should be strictly applied when making a diagnosis of SSA in the rectum.
Category: Gastrointestinal

Wednesday, March 2, 2011 9:30 AM

Poster Session V # 30, Wednesday Morning

 

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