Formalin-resistant leukocyte surface antigens in the diagnosis of cutaneous malignant lymphomas

Immunophenotyping of routinely embedded lymphoma biopsies, increasingly used in nodal lymphomas, has not been systematically performed in cutaneous lymphomas. Eight monoclonal antibodies were tested directed against formalin resistant antigens (T cell biased: UCHL1, MT1; B cell biased: 4KB5, L26, Ki-B3; HLA-class II: CBL 120; activation antigens: Ber-H2; myeloid biased: Mac 387, M1) in cutaneous T (N = 29) and B (N = 10) cell lymphomas and pseudolymphomas (N = 9). UCHL1 and MT1 showed a high specificity and sensitivity. B cell-restricted antibodies L26 and 4KB5 showed the best sensitivity and specificity among the B cell-associated antibodies; Ki-B3 showed aberrant expression on T cells in some cases. Ber-H2 (CD30) was demonstrated in most cases of large cell anaplastic lymphoma and single cases of other lymphomas and lymphomatoid papulosis. Class II antigen expression, as determined by CBL 120, showed good specificity but low sensitivity, and antibodies directed against myeloid antigens did not react with tumor cells.