Gene analysis in 18 cases of cutaneous lymphoid infiltrates of uncertain significance.

Abstract

Patients with cutaneous lymphoid infiltrates that appear reactive histologically and immunophenotypically may develop clinically overt cutaneous lymphoma, suggesting the possibility of misdiagnosis by classical methods. We investigated DNA rearrangement in such cases of lymphoid infiltrates of uncertain significance to determine whether this more sensitive method could detect an occult monoclonal lymphoid proliferation. Skin biopsy specimens were taken from 18 cutaneous lymphoid infiltrates diagnosed as reactive on the basis of clinical, histopathological, and immunohistochemical criteria. Specimens included 12 cases with mixed lymphoid infiltrates rich in polytypic B cells and inconstant follicle formation and 6 cases with exclusive T-lymphoid infiltrates. Southern blot analysis for immunoglobulin and T-cell-receptor beta-chain gene rearrangements was performed in all cases. No specimen showed T-cell-receptor beta-chain gene rearrangement. Clonal immunoglobulin gene rearrangement was demonstrated in one case with polytypic B cells, but no clinical malignancy has appeared 19 years after disease onset duration and 7 years after detection of the B-cell clone. In the present series, the results suggest that histological and immunohistological criteria are appropriate to establish the diagnosis of most cases of cutaneous lymphoid infiltrates. The detection of a B-cell clone is remarkable 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 proliferation, indicating that a long-term follow-up is necessary.