[719] Pseudoinvasion and Dysplasia in Peutz-Jeghers Hamartomatous Polyps

Meghan P Riley, Zhaohai Yang. Penn State Milton S. Hershey Medical Center, Hershey, PA

Background: Peutz-Jeghers syndrome (PJS) is an autosomal dominant genetic disorder characterized by the development of hamartomatous polyps in the gastrointestinal tract (GI) and mucocutaneous pigmentation. It is associated with an increased risk of GI and non-GI malignancies. However, there is still controversy about the magnitude of risk of GI carcinoma. Pseudoinvasion, or misplacement of the epithelium, is known to occur in PJS polyps and may closely mimic adenocarcinoma, which may lead to overdiagnosis of dysplasia and carcinoma.
Design: Sixty-six hamartomatous polyps from 17 PJS patients were retrospectively reviewed, which included 8 (12%) from stomach, 44 (67%) from small intestine, and 14 (21%) from large intestine. The clinicopathological features of each polyp including dysplasia and pseudoinvasion were assessed. Immunohistochemical staining for Ki67 and p53 was performed on polyps that were suspicious for dysplasia.
Results: Twenty-three polyps (35%) from 13 patients (76%) showed pseudoinvasion, and all of them were in the small intestine. Low-grade dysplasia or indefinite for dysplasia was diagnosed in 3 of the 23 polyps (13%) based on routine H&E stain; however, immunostain for Ki-67 and p53 showed a pattern indistinguishable from normal epithelium. No GI carcinoma was identified in any of the patients. In 3 of the 17 patients (18%) with pseudoinvasion, the clinical presentation was suspicious of malignancies thus the polyps were surgically resected. In each case, there was extensive pseudoinvasion into the serosa, without any evidence of dysplasia or carcinoma. Postsurgical follow-up (1 -12 months) revealed no complications or carcinoma.
Conclusions: Although PJS is traditionally thought to have an increased risk of GI malignancy, our data suggests that true dysplasia or carcinoma is distinctly rare in PJS polyp. However, deep pseudoinvasion is more common which may have led to an overdiagnosis of dysplasia and carcinoma.
Category: Gastrointestinal

Wednesday, March 6, 2013 1:00 PM

Poster Session VI # 105, Wednesday Afternoon


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