AITL cases were more likely than PTCL-TFH cases to contain expanded CD21-positive follicular dendritic cell meshworks, clear cell cytology and polymorphous inflammatory background; however, there was a significant (P<0.005) Kruskal-Wallis trend in all morphologic variables between the 3 groups suggesting a continuum from PTCL-NOS to PTCL-TFH to AITL.
Among these, CCR4 expression and the CD21(+) network in RHOA-mutated AITL cases were more extensive than in the RHOA mutation-negative AITL cases (P<0.05).