DIFFERENTIATION OF PRIMARY AND SECONDARY CUTANEOUS B-CELL LYMPHOMA BYSOUTHERN BLOT ANALYSIS

Malignant B-cell lymphomas represent a heterogenous group of lymphoret icular disorders that involve the skin in about 20% of reported cases. Skin involvement may be primary or secondary tie, the result of hemat ogenous spread). Primary cutaneous B-cell lymphomas (PCBCLs) are thoug ht to take a comparatively favorable course, respond readily to nonagg ressive treatment, and lack evidence of extracutaneous spread. Nine pr imary B-cell lymphomas (7 centrocytic or centroblastic follicular, 1 i mmunoblastic, 1 centroblastic), three secondary (follicular) cutaneous B-cell lymphomas (SCBCLs) and two pseudolymphomas were studied, Stagi ng revealed that bone marrow was involved only in SCBCLs. Centrocytes were detected in blood smear preparations of all SCBCLs. All lymphomas were treated with local irradiation. Patients with primary centroblas tic and immunoblastic cutaneous lymphomas and those with secondary lym phomas received additional chemotherapy. Pseudolymphomas were treated by simple excision. Patients were monitored on average for 55 months. During this period, no patients with PCBCLs exhibited cutaneous relaps es or hematogenous spread, In contrast, all patients with SCBCLs exper ienced cutaneous relapses. Peripheral blood, bone marrow, and skin sam ples from all patients were subjected to Southern blot analysis using a JH probe. Clonal rearrangement was found in all skin samples investi gated except specimens from pseudolymphomas. Peripheral blood and bone marrow samples were positive in SCBCLs (the rearrangement pattern was different from that of the skin samples for two of the three patients ), whereas it was negative in all PCBCLs and pseudolymphomas. In concl usion, Southern blot analysis of peripheral blood may be useful in dif ferential diagnosis of PCBCLs and SCBCLs and a prognostic marker, Furt hermore, these data confirm the comparatively favorable clinical cours e of PCBCLs and suggest that in these cases, local irradiation can be considered adequate treatment, whereas SCBCLs require additional syste mic therapy.