Mucosal Schwann cell "hamartoma": clinicopathologic study of 26 neural XXXX and mucosal neuromas.

@entity1 @entity1127 @entity3670 @entity3292 @entity1265 @entity911 @entity74 @entity14 @entity4786 @entity2280 @entity2950 @entity2281
@entity1127 containing @entity2281 -positive neural proliferations in the lamina propria that lack ganglion cells have been variously referred to as " @entity2950 " or " @entity3292 ." However, these lesions have not been systematically examined, and whether they are associated with type 1 @entity4786 ( @entity1265 ) or other @entity74 is unknown. The aim of this study was to evaluate the clinicopathologic and immunohistochemical features of these lesions, in comparison to @entity14 from known @entity1265 @entity1 . Morphologically similar lesions from 26 @entity1 (mean age, 62 y; range, 46 to 88 y; male/female ratio, 10/16) were retrieved from surgical pathology and consult files. Clinical and endoscopic data were obtained, and immunohistochemistry for @entity2281 protein, glial fibrillary acidic protein, neurofilament protein (NFP), epithelial membrane antigen, @entity3670 , @entity2280 , smooth muscle actin, and KIT was performed. The findings were compared with those in mucosal biopsies of 5 submucosal @entity3292 from @entity1265 @entity1 . All 26 @entity1127 were sessile, ranging from 1 to 6 mm in size (mean, 2.5 mm). Most arose in the distal colon (15 rectosigmoid, 7 descending, 2 transverse, and 2 ascending), and were incidentally found at screening colonoscopy. After a mean follow-up of 6.5 years (range, 3 mo to 17.5 y), none of the @entity1 developed other @entity1127 , and none had evidence of @entity1265 or other @entity74 . Histologically, the lamina propria of the @entity1127 contained a diffuse cellular proliferation of uniform bland spindle cells with elongated, tapering nuclei, abundant, dense eosinophilic cytoplasm, and indistinct cell borders, entrapping adjacent crypts. No nuclear atypia, pleomorphism, mitotic activity, or associated ganglion cells were observed. All showed strong staining for @entity2281 protein in essentially 100% of cells. NFP highlighted rare axons in 7 lesions. All other markers were negative. The 5 @entity3292 showed similar histologic features, but were generally less uniformly cellular, showed some intralesional heterogeneity, and showed less extensive staining for @entity2281 protein; all contained scattered NFP-positive axons. In summary, solitary colorectal @entity1127 containing pure Schwann cell proliferations in the lamina propria are not associated with @entity1265 . Distinguishing these lesions from @entity1265 -associated @entity3292 is difficult based on histologic features; the presence of an underlying submucosal nodule or mass should be excluded endoscopically, and immunohistochemistry should be performed. Although their nature is uncertain, we propose the interim designation "mucosal Schwann cell 'hamartoma'" to avoid @entity911 with the neural lesions that have significant associations with @entity74 .
