Evaluation of intraepithelial lymphocytic counts in pediatric duodenal endoscopic biopsies by routine staining and CD3 Immunostaining

Aim
This study aimed to compare the intraepithelial lymphocytic (IEL) counts by hematoxylin and eosin (H&E) and by CD3 immunohistochemistry (IHC) in pediatric duodenal biopsies during routine diagnostic practice and to evaluate the interobserver variability between both methods.
Materials and methods
A retrospective study was conducted on 64 pediatric duodenal biopsies received from January 2017 to December 2018 at the Pathology Laboratory of Ain Shams University Hospitals and classified into three groups: group 1 with established coeliac disease by previous biopsy, group 2 with newly received cases suspicious of coeliac disease with positive anti-tissue transglutaminase with present or absent villous atrophy, and group 3 with normal or unknown anti-tissue transglutaminase. IEL count was evaluated by routine H&E and by CD3 immunohistochemistry by the two authors and categorized into normal (<25 lymphocytes), mildly raised (25–40 lymphocytes), and markedly raised (>40 lymphocytes). Agreements between stains, as well as interobserver agreement, were calculated.
Results
The overall mean IEL count per 100 enterocytes for H&E was 21.86 [95% confidence interval=18.34–25.38], and for IHC by CD3, it was 26.19 (95% confidence interval=22.52–29.85). The difference was highly significant (=0.001), with highly significant substantial agreement between H&E and CD3 IHC results (=0.001; =0.694). The overall interobserver agreement for H&E was almost perfect among the cases of all groups, and among groups 1, 2, and 3 (=0.946, 0.825, 0.831, 1, respectively). The overall interobserver agreement for CD3 IHC was almost perfect among the cases of all groups, and among groups 1, 2, and 3 (=0.975, 1, 1, and 0.956, respectively).
Conclusion
CD3 can aid in the detection of IELs but only in the proper clinical and serological setting.