Clonal B-cell proliferations developing in the background of primary cutaneous CD4+ small/medium T-cell lymphoproliferative disorder: A case series.

Clonal B-cell proliferations and B-cell lymphomas may co-occur in the background of follicular helper T-cell (TFH)-derived lymphomas, most associated with EBV, which has been a well-known fact for many years in the prototypical entity "TFH lymphoma, angioimmunoblastic-type." Primary cutaneous CD4+ small/medium T-cell lymphoproliferative disorder (CD4+ PCSM-LPD) is also a TFH-derived clonal proliferation. We searched the archives and identified four cases of CD4+ PCSM-LPD with accompanying clonal B-cell proliferation (one of which showed EBER positivity), and one longstanding case of CD4+ PCSM-LPD, in the background of which a B-cell lymphoma had developed. These five cases broaden experience on CD4+ PCSM-LPD with accompanying B-cell proliferations and also support routine evaluation of these cases with EBV in situ hybridization, to better determine whether or not there is an association with EBV.