Immunohistochemical profile of cutaneous B-cell lymphoma on cryostat and paraffin sections.

Thirty cases of primary (23 cases) and secondary (seven cases) cutaneous B-cell lymphoma (CBCL) were studied by immunohistochemistry using a selected monoclonal antibody (MoAb) panel on both cryostat and paraffin sections. On cryostat sections all CBCL so tested were positive for surface membrane immunoglobulins (IgMk most often) and B-cell antigens (CD22+, CD37+) with a variable T-cell-reactive component identified by MoAbs against T-cell antigens (CD2, CD3, CD4, CD5, CD8). CD4-positive stromal T-cells were usually more numerous than CD8-positive cells. A strong (50-75% of total cells) stromal T-cell (CD2+, CD3+) reaction was found in centroblastic-centrocytic lymphoma. Small numbers of CD1+ Langerhans cells were found in most cases, but they were present in large numbers in follicular lymphoma. On paraffin sections, a combination of MoAbs against B-associated antigens (LN-1, MB2) identified B-cell lineage in virtually all cases of CBCL. CBCL was negative for MoAbs against T-associated antigens (MT1, UCHL1) with rare exceptions (two cases). However, MT1 and UCHL1 combined identified the T-cell nature of all cases of nonepidermotropic, nonmycosis T-cell lymphoma, which were initially predictive of B-lineage by histologic pattern.