Appendiceal mucosal Schwann cell proliferation: a putative histologic marker of appendiceal diverticular disease.

Recognition of an appendiceal diverticulum is important because of its association with an appendiceal neoplasm. The incidence of mucosal Schwann cell proliferation in 24 cases of appendiceal diverticular disease, 17 serrated polyps, 4 cases of mucosal hyperplasia, and 45 normal appendices was determined. Ten (42%) of 24 cases with diverticula, 2 (50%) of 4 cases of mucosal hyperplasia with concurrent surface low-grade dysplasia, and 9 (20%) of 45 cases of normal appendices showed mucosal Schwann cell proliferation. It was not seen within the 17 cases of serrated polyps. Mucosal Schwann cell proliferation is common in appendiceal diverticular disease and may serve as a histologic marker for the presence of an appendiceal diverticulum. Thus, when routine histologic sections of a removed appendix demonstrate Schwann cell proliferation, further examination of the specimen may detect possible coexisting diverticular disease, which in turn may be associated with appendiceal neoplasms and epithelial dysplasia.