Assessment of intraepithelial lymphocytes count in potential celiac disease

Intraepithelial lymphocytes (IELs) count, central for coeliac disease (CD) diagnosis, can be performed either directly on hematoxylin and eosin (H&E)–stained paraffined sections or on optimal-cutting-temperature-compound (OCT)-embedded frozen sections stained by immunohistochemistry (IHC) with anti-CD3. We evaluated the concordance in Marsh grading between these two techniques on a large sample of sections. A total of 280 patients with a normal intestinal architecture, 210 potential celiac disease (PCD) patients, and 70 controls (CTR) were included. At the H&E histological evaluation, 136/280 were classified as Marsh-0 (showing < 25 IELs/100 enterocytes) and 144 Marsh-1, while at the IHC evaluation, 191 were classified as Marsh-0 (showing ≤ 34 CD3+/mm of epithelium) and 89 Marsh-1. The overall concordance was 66.8% (48.6% Marsh-1 and 86% Marsh-0) with a Cohen Kappa value of 0.33. In the PCD group, the overall concordance was 63% (45.6% Marsh-1 and 84% Marsh-0) with a Cohen Kappa value of 0.26, while in the CTR group it was 77% (60% Marsh-1, 90% Marsh-0) with a Cohen Kappa value of 0.54. Differences between the two groups were statistically significant (p < 0.05). In conclusion, the concordance of IELs counts between histological and IHC evaluation is low (Kappa Cohen 0.54) in no-CD and even more in PCD patients (0.26). Caution must be paid when classifying a patient as Marsh-0 or Marsh-1 according to the technique used.