Lymphoma versus pseudolymphoma of the skin: gene rearrangement study of 21 cases with clinicopathologic correlation.

Abstract

Diagnosis of cutaneous lymphoma in the absence of systemic lymphoma may be difficult. Reactive lymphoid lesions can mimic lymphoma clinically and histologically and have been designated pseudolymphomas. Our purpose was to analyze lymphoid gene rearrangements in cutaneous lymphoproliferative lesions and to correlate these findings with the histologic, immunophenotypic, and clinical profile. We examined 21 cases of lymphoproliferative lesions that developed in skin and performed molecular rearrangement analysis of T-cell receptor and immunoglobulin genes. We examined identical tissues by histologic and immunophenotypic criteria and conducted follow-up clinical evaluation of all patients. Clonal rearrangements of immunoglobulin (seven cases) or T-cell receptor (two cases) gene were detected in 9 of 21 patients. No specific histologic or immunophenotypic feature was consistently associated with a clonal lymphoid gene rearrangement. Systemic lymphoma developed in one patient in whom a clonal rearrangement within the immunoglobulin gene was identified. Gene rearrangement analysis may be helpful in differentiating primary cutaneous lymphoma from pseudolymphoma. The chronic clinical course of patients with clonal lymphoid gene rearrangements supports a lack of correlation between clonality and biologic aggressiveness.