Proximal small-bowel mucosal villous intraepithelial lymphocytes.

Small-bowel biopsies are routinely obtained from adult patients as a screening tool to evaluate the possibility of gluten sensitivity (GS). Previous morphological criteria of GS including completely flattened villi are usually absent. In the context of screening for GS, an altered distribution density pattern of villous intraepithelial lymphocytes (IELs) is probably the most sensitive morphological feature to suggest the possibility of GS and prompt the initiation of further medical evaluation. Altered villous IEL density distribution is a more sensitive screening feature than villous IEL counts. With increased small-bowel GS screening biopsies, occasional adults without GS with complete villous flattening and numerous villous IELs are encountered. These patients are usually incorrectly diagnosed with GS. However, they do not respond to a gluten-free diet and slowly improve over months.