Immunohistochemical classification of cutaneous lymphomas and pseudolymphomas

: We investigated 46 cases of cutaneous lymphoma and pseudolymphoma by immunohistochemical methods using a panel of monoclonal antibodies. Of the cutaneous T cell lymphomas, 2 did not show the classic helper phenotype but revealed a predominance of suppressor cells in one case and of immature thymocytes in the other. Cutaneous B cell lymphomas of low-grade malignancy were characterized by the presence of completely developed T zones between the B cell areas. B cell lymphomas of high-grade malignancy revealed an immunohistologically homogeneous infiltrate. Cutaneous pseudolymphomas can be classified in T cell pseudolymphomas (lymphocytic infiltration, lymphomatoid papulosis) and B cell pseudolymphomas. Lymphadenosis cutis benigna with germinal center cell differentiation was clearly distinguishable from other B cell pseudolymphomas, which are considered to comprise mainly peripheral B lymphocytes. Immunohistological methods are obviously useful in the classification of lymphoproliferative diseases of the skin and can make a contribution to increasing our understanding of them.