The etiology of PLEVA is unknown, but it is presumed to be associated with an effector cytotoxic T-cell response to either an infectious agent or a drug.11Three studies have shown that most PLEVA cases (100% [3/3]; 65% [13/20]; and 57% [8/14]) demonstrate T-cell clonality,12-14 and some have suggested that PLEVA may be a T-cell lymphoproliferative disorder.12,13 Additionally, in a case report of 2 children with PLEVA who progressed to cutaneous T-cell lymphoma, the authors suggested that PLEVA may be related to nonaggressive cutaneous T-cell lymphoma.15 Of note, T-cell clonality, often found through the analysis of T-cell receptor gene rearrangement, is not an absolute criterion for determining malignancy, as some benign conditions may have clonality.16 However, in another study, clonality was found in only 1 of 10 cases of PLEVA, suggesting that PLEVA stems from an inflammatory reaction to infectious or other triggering agents.17
Four cases of FUMHD with monoclonality have been reported,4,7,8 and some researchers propose that FUMHD may be a subset of cutaneous T-cell lymphoma.7 However, 2 other cases of FUMHD did not show monoclonality of T cells,5,18 suggesting that FUMHD may represent an inflammatory disorder, rather than a lymphoproliferative process of T cells.18 Given the controversy surrounding the clonality of FUMHD, T-cell gene rearrangement studies were not performed in our case.