[585] Early Colorectal Perineurioma: A Frequently Missed Lesion?

GM Groisman, M Amar, A Meir. Hillel Yaffe Medical Center, Hadera, Israel

Background: Typical colonic perineuriomas are characterized by a stromal mucosal proliferation of monomorphic plump to spindle cells leading to obvious separation and disorganization of frequently serrated colonic crypts. In our experience however, a sizable amount of the cases show only a minimal degree of stromal proliferation and crypt separation. Accordingly, these perineuriomas can be misdiagnosed as hyperplastic polyps or mucosal tags. To bring attention to this previously undescribed morphological variant of colonic perineurioma (early perineurioma), we report the histological and immunohistochemical findings of a series of 11 cases.
Design: Eleven cases diagnosed as early perineuriomas were retrieved from the authors' files from among 49 cases of colonic perineuriomas. H&E stained sections were re-examined and immunostains for perineurial markers including epithelial membrane antigen (EMA), claudin-1, glut-1 and collagen type IV were performed. Clinical and endoscopic data were obtained from the patients' charts.
Results: Seven patients were male and 4 female (age range 44-71 yrs; median 62). All lesions were found during screening colonoscopy for colorectal carcinoma. Polyp size ranged from 2 to 4 mm. Eight (73%) were located in the sigma and in 5 (45%) cases there was an associated hyperplastic polyp. Histologically, early perineuriomas were characterized by small, non-contiguous nests or bundles of monomorphic plump or spindle stromal cells with eosinophilic cytoplasm and oval to fusiform nuclei, leading to minimal separation of straight, parallel crypts. In 8 (72%) cases, the crypts were serrated. In all cases, the foci of stromal proliferation expressed all 4 perineurial markers.
Conclusions: Early perineurioma is a morphologic variant of colonic perineurioma characterized by a limited proliferation of perineurial cells. This lesion can be misdiagnosed as hyperplastic polyp or mucosal tag. A panel of perineurial markers helps in reaching an accurate diagnosis.
Category: Gastrointestinal

Wednesday, March 11, 2009 9:30 AM

Poster Session V # 72, Wednesday Morning