Validity of Intraepithelial Lymphocyte Count in the Diagnosis of Celiac Disease: A Histopathological Study

The gold standard for diagnosis of Celiac disease (CD) is histological evidence of a small intestinal biopsy together with positive serology. Modified Marsh classification utilizes the histological parameter of intraepithelial lymphocyte (IEL) count in the diagnosis of CD. The reported upper limit of normal IEL in the duodenum varies from 20-40 per 100 epithelial cells (EC). The objectives of the study are to determine the normal upper limit of IEL in the duodenum and assess the diagnostic accuracy of existing criteria of IEL counts to diagnose CD. A retrospective analysis of histopathological records of duodenal biopsies reported as normal (control group, n=38) and consistent with CD (n=37) formed the basis of the study. IEL were counted in an uninterrupted length of surface epithelium and villous tips from formalin fixed, paraffin embedded, Haematoxylin and Eosin stained biopsies under the light microscope (X400 magnification). In the control group the mean IEL/100EC was 3.81(upper limit of normal = 7.78) and the mean IEL/villous tip was 0.96 (upper limit of normal = 3.5). In CD the mean IEL/100EC and mean IEL/villous tip were 20.93 and 6.83 respectively. The upper limit of normal IEL/100EC, mean IEL/100EC in CD and the villous tip IEL count in both the control and CD groups were considerably lower than those reported in other studies. The ethnicity, country of origin and environmental factors may be partly responsible for this observation. If high cut off values of IEL/100EC is taken to diagnose CD many cases may be under diagnosed, particularly when the upper limit of the normal IEL count is lower for that population and region, highlighting the importance of a multidisciplinary approach in the diagnosis of CD.