Significance of Intraepithelial Lymphocytosis in Small Bowel Biopsy Samples with Normal Mucosal Architecture

Objectives: The aim of this study was to determine the specificity of increase in intraepithelial lymphocytes (IELs) with normal villous architecture in small bowel biopsy samples for diagnosis of gluten sensitivity (GS) and its significance in the absence of GS.

Methods: Small bowel biopsy samples from 43 patients with increased IELs and no other pathology were reviewed. Patients with prior diagnosis of GS were excluded. A group of 46 patients with normal duodenal biopsy during the same period served as controls. The clinical records of patients and controls were examined for presenting symptoms, laboratory tests, and final clinicopathological diagnosis. Immunohistochemical characterization of IELs was performed in 13 cases.

Results: Four (9.3%) patients had GS based on positive IgA antiendomysial antibodies (n = 3) and favorable response to gluten-free diet (n = 4). One patient (2.2%) had partially treated tropical sprue; six patients (14%) had disorders of immune regulation including Hashimoto's thyroiditis (n = 2) and one case each of Graves' disease, rheumatoid arthritis, psoriasis, and multiple sclerosis; and six patients (14%) were on nonsteroidal anti-inflammatory drugs (NSAIDs). In contrast, none of the control subjects had GS (p = 0.05), tropical sprue, or immunoregulatory disorders (p = 0.011), and one (2.2%) was on NSAIDs (p = 0.04). Increased IELs were also observed in Crohn's disease, lymphocytic/collagenous colitis, and bacterial overgrowth, but the association did not reach statistical significance. Histological features (number and distribution of IELs, crypt mitoses) and immunophenotypic analysis of IELs did not reliably distinguish GS-related from non-GS-related causes of increased IELs.

Conclusions: Intraepithelial lymphocytosis in an otherwise normal small bowel biopsy is somewhat nonspecific, but in nearly 10% of cases can be the initial presentation of GS. Therefore all patients with this finding should be investigated for GS. Increased IELs may also be associated with autoimmune disorders and NSAIDs.