The clinical significance of duodenal lymphocytosis with normal villus architecture.

The finding of increased intraepithelial lymphocytes with normal villous architecture (Marsh I lesion) is seen in up to 3% of duodenal biopsies. The differential diagnosis includes a wide range of possibilities, including celiac disease, bacterial overgrowth, nonsteroidal antiinflammatory drug damage, reaction to Helicobacter pylori infection, tropical sprue, and chronic inflammatory bowel disease. To highlight the histologic features of the Marsh I lesion, review the diseases and conditions associated with that finding, and to provide pathologists with a rationale and a template for how to identify and report such cases. A review of the literature regarding the histologic features and clinical associations of Marsh I lesions. Marsh I lesions are a nonspecific finding associated with a number of disease conditions. Historically, between 9% and 40% of cases have been shown to represent celiac disease. Current data do not suggest histologic features to differentiate between diseases associated with this histologic change.