CD56/neural cell adhesion molecule expression in primary extranodal Ki-1/CD30+ lymphoma. Report of a pediatric case with simultaneous cutaneous and bone localizations.

We describe the clinicopathologic features of an unusual case of CD30+/CD50+ T-cell lymphoma in a child who presented with simultaneous primary extranodal cutaneous and bone localizations. The expression of CD56 (neural cell adhesion molecule, or NCAM) is rare in non-Hodgkin's lymphomas other than in a group of haematopoietic/lymphoid neoplasms of natural killer and natural killer-like T-cells, which usually involve extranodal sites and often pursue an aggressive clinical behavior. Coexpression of CD30 and CD56 in T-cell lymphomas is exceedingly rare, and its biological significance is unknown. Our patient responded well to an intensive chemotherapy regimen, and she is now in complete remission 4 years after discontinuation of chemotherapy. Expression of NCAM could be regarded as responsible, in part, for the extranodal localization of lymphoma cells; expression of CD56 also might contribute to the definition of a subset of CD30+ lymphomas with distinctive clinicopathologic features.