CD8A and cranioectodermal dysplasia: Depending on the absence or presence of aberrant intraepithelial lymphocytes (IELs; lacking surface CD3 and generally CD8 but expressing intracellular CD3), RCD can be classified into two types: RCD type I (RCD-I), which mimes a CeD at diagnosis, and RCD II, which is characterized by the presence of a percentage of aberrant IELs, with monoclonality of TCR in the majority of cases, which is above 20% using flow cytometry and 50% using immunohistochemical analysis [64,65].