GENE ANALYSIS IN 18 CASES OF CUTANEOUS LYMPHOID INFILTRATES OF UNCERTAIN SIGNIFICANCE

Background and Design.-Patients with cutaneous lymphoid infiltrates th at appear reactive histologically and immunophenotypically may develop clinically overt cutaneous lymphoma, suggesting the possibility of mi sdiagnosis by classical methods. We investigated DNA rearrangement in such cases of lymphoid infiltrates of uncertain significance to determ ine whether this more sensitive method could detect an occult monoclon al lymphoid proliferation. Methods and Patients.-Skin biopsy specimens were taken from 18 cutaneous lymphoid infiltrates diagnosed as reacti ve on the basis of clinical, histopathological, and immunohistochemica l criteria. Specimens included 12 cases with mixed lymphoid infiltrate s rich in polytypic B cells and inconstant follicle formation and 6 ca ses with exclusive T-lymphoid infiltrates. Southern blot analysis for immunoglobulin and T-cell-receptor beta-chain gene rearrangements was performed in all cases. Results.-No specimen showed T-cell-receptor be ta-chain gene rearrangement. Clonal immunoglobulin gene rearrangement was demonstrated in one case with polytypic B cells, but no clinical m alignancy has appeared 19 years after disease onset duration and 7 yea rs after detection of the B-cell done. Concluions.-In the present seri es, the results suggest that histological and immunohistological crite ria are appropriate to establish the diagnosis of most cases of cutane ous lymphoid infiltrates. The detection of a B-cell clone is remarkabl e by absence of clinical malignancy, suggesting that such a discovery does not necessarily mean an aggressive evolution. Nevertheless, there is presently no way to predict the prognosis of a clonal lymphoid pro liferation, indicating that a long-term follow-up is necessary.