[740] Colorectal Granular Cell Tumor; a Study of 24 Cases

AD Singhi, E Montgomery. Johns Hopkins Hospital, Baltimore, MD

Background: Granular cell tumor (GCT) is commonly located in the subcutaneous tissue and oral cavity, and uncommon in the gastrointestinal tract, where the majority arise in the esophagus with over-representation in African Americans (AA). However, experience with GCTs found in the colorectum is quite limited. We report the clinicopathologic features of the largest series to date of colorectal GCTs.
Design: We reviewed the clinicopathologic features of 24 colorectal GCT seen at our institution between 1995-2009, which included 23 biopsies and one low anterior resection.
Results: Review of the clinical features of all 24 cases from 22 patients identified an equal gender distribution (12 males and 10 females) ranging in age from 31 to 60 years (mean 51 years; median 53 years) with a modest Caucasian predominance (14/22, 64%; our overall patient population is 67% white). The majority of colorectal GCT involved the right colon (18/24, 75%) ranging in size from 0.2 to 1.8 cm (mean 0.6 cm; median 0.5 cm). Most neoplasms were encountered on routine colonoscopy (14/22, 64%), however three patients presented with hematochezia, three with changing bowel habits, one with diverticular disease and one with appendicitis. Of the eighteen cases available for histologic review, the tumors were predominantly infiltrative (12/18, 67%) involving either the mucosa (7/18, 39%), submucosa (8/18, 44%) or both (3/18, 17%). The microscopic features were similar to those of GCTs found elsewhere, but many of the neoplasms differed by displaying nuclear pleomorphism (8/18, 44%), lymphoid cuffs (8/18, 44%), and focal calcification (5/18, 28%). Some had reactive mucosal surface changes (6/18, 33%), including one initially misdiagnosed as a tubular adenoma. Both mitoses and necrosis were absent. On immunochemistry, sixteen of the neoplasms were stained for S-100 and all cases demonstrated positive staining. Follow-up information was present for seventeen patients (17/22, 77%) with two documented recurrences within the cecum and no metastases.
Conclusions: While infrequently found in the colorectum, GCT typically present incidentally on routine colonoscopy and involve the right colon; they are not over-represented in AA patients. The majority of GCTs have an infiltrative growth pattern and tend to display nuclear pleomorphism, a lymphoid cuff, focal calcification and reactive mucosal surface changes, which in our experience, may lead to misdiagnosis on colorectal mucosal biopsies. Although GCTs were benign tumors in this series, we identified two recurrences in our series and therefore, follow-up may be warranted.
Category: Gastrointestinal

Tuesday, March 23, 2010 1:00 PM

Poster Session IV # 83, Tuesday Afternoon

 

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