[686] Inflammatory Fibroid Polyps of the Gastrointestinal Tract: Spectrum of Clinical, Morphological, and Immunohistochemistry Features

Ta-Chiang Liu, Ming-Tseh Lin, Elizabeth A Montgomery, Aatur D Singhi. Washington University, St. Louis, MO; Johns Hopkins University, Baltimore, MD; University of Pittsburgh, Pittsburgh, PA

Background: Inflammatory fibroid polyps (IFP) are rare benign tumors that can occur throughout the gastrointestinal tract. While part of the molecular pathogenesis of these lesions has been characterized, their morphologic features often vary. We report the clinicopathologic findings of the largest series of IFPs to date.
Design: Medical record, histology sections, and available immunostains of IFP cases diagnosed at Johns Hopkins U. between 1999 and 2012 were reviewed. Histologic and immunohistochemical characteristics were documented and semi-quantification (0: none, 1+: weak; 2+ moderate; 3+: strong) were applied for each feature.
Results: A total of 83 IFPs were collected between 1999 and 2012, including 64 biopsies and 19 resections. A review of the clinical features identified a modest female predominance (47; 57%) with patients ranging from 26 to 87 years (mean, 60 years). Involved sites include esophagus (n = 2), stomach (n = 31; mainly antrum), small intestine (n = 15), appendix (n = 1), large intestine (n = 33; majority within the rectosigmoid), and anal canal (n = 1). While most had a nonspecific presentation, those with small intestinal lesions frequently presented with intussusception. Grossly, the tumors ranged in size from 0.2 to 4.2 cm (mean, 1.7 cm). Histologically, IFPs were centered within the submucosa in all resection specimens but mucosal entension was found in 74 of 83 (89%) cases. The tumors varied in both cellularity and degree of vascularity. However, the characteristic feature of perivascular onion-skinning was present in only 54% (45/83). Importantly, a short fascicular growth pattern was noted in 36% (30 of 83) of cases, while both features were present in 14 cases (17%). Eosinophils were present in 94% (78 of 83) of cases but varied widely in number from abundant (20/hpf) to sparse (1/hpf). Interestingly, in those cases with sparse eosinophils, prominent hyalinization was also present (11 of 78, 14%). In addition, while the majority of IFP expressed CD34, 6 of 44 (14%) did not. No associated dysplasia or malignancy was seen.
Conclusions: IFPs represent a diverse set of submucosal-based lesions that commonly extend into the mucosa, making them amenable to endoscopic biopsy. While their classic histologic features of perivascular onion skinning and predominance of eosinophils are well-described, they may alternatively present with a short fascicular growth pattern, a sparse number of eosinophils and prominent hyalinization.
Category: Gastrointestinal

Wednesday, March 6, 2013 1:00 PM

Poster Session VI # 78, Wednesday Afternoon


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