Accurate classification of RCD requires flow cytometry

We read with interest the article of Liu et al in Gut , in which the authors emphasise the need for monitoring of clonality and intraepithelial lymphocyte (IEL) immunophenotype in the surveillance of refractory coeliac disease (RCD).1 The authors state there is no consensus on the cut-off of aberrant cells distinguishing between non-complicated coeliac disease (CD), RCD type I (RCDI) and RCD type II (RCDII). However, in 2000 it was shown that based on the number of aberrant T cells, CD can be distinguished from RCD by immunohistochemistry.2 Furthermore, using flow cytometry, Verbeek defined a clinically well-validated cut-off of 20% IELs as being diagnostic for RCDII.3 In their paper, the authors describe that a high percentage of patients (80%) progress from RCDI to RCDII. This is somewhat …