Co-expression of CD56 and CD30 in lymphomas with primary presentation in the skin: clinicopathologic, immunohistochemical and molecular analyses of seven cases.

BACKGROUND Natural killer and natural killer-like T-cell lymphomas presenting in the skin usually demonstrate aggressive behavior, an angiocentric distribution and a characteristic immunophenotype. In contrast, primary cutaneous CD30+ lymphoproliferative disorders form a heterogeneous spectrum including anaplastic large cell lymphomas, the majority of which display a good prognosis. Lymphomas with co-expression of CD56 and CD30 are extremely rare and the significance of this co-expression is unknown. METHODS Seven retrospectively identified cases of lymphomas with co-expression of CD56 and CD30 presenting in the skin comprise this study. Immunohistochemistry, in situ hybridization for Epstein-Barr virus and T-cell receptor gene rearrangement studies were performed on paraffin sections. RESULTS This subset of cutaneous lymphomas showed a variable clinical course that ranged from resolution without treatment, treatment-failure and recurrence, to death from disease. Histologic, immunophenotypic and molecular studies were of limited utility in predicting prognosis. CONCLUSIONS Cutaneous lymphomas co-expressing CD56 and CD30 share many clinicopathologic features with natural killer and natural killer-like T-cell lymphomas or anaplastic large cell lymphomas, two entities with widely disparate clinical behavior. It is important to recognize that these lymphomas may behave more aggressively than primary cutaneous anaplastic large cell lymphomas do. Longer follow-up and further investigations on larger numbers of cases are necessary to fully characterize this rare subset of cutaneous lymphomas.