Erythema multiforme in a patient with T cell chronic lymphocytic leukemia.

A patient with T4+ (helper-inducer) T cell chronic lymphocytic leukemia developed an erythema multiforme-like eruption, the diagnosis of which was supported by routine light microscopic findings. Immunopathologic studies using monoclonal antibodies demonstrate that despite an overwhelming majority of leukemic T4+ cells in the peripheral blood and dermal infiltrate, the predominant cells in the epidermal infiltrate are T8+ (cytotoxic-suppressor) cells. These findings are different from those seen in epidermotropic T cell leukemic infiltrates and are similar to those previously reported in erythema multiforme. Thus it is likely that the leukemic T4+ cells are participating in this cutaneous hypersensitivity reaction along with residual, normal T8+ cells.