Immunophenotypic and genotypic characterization of lymphomatoid papulosis.

Abstract

Lymphomatoid papulosis (LyP) is a chronic dermatosis that histologically resembles malignant lymphoma. Thus far, only a few cases of LyP have been characterized in detail with regard to immunophenotype, genotype, and karyotype. Our purpose was to study seven patients with LyP and compare the results to those reported in the literature. Skin biopsy specimens were analyzed by frozen section immunohistochemical and molecular biologic techniques. Cytogenetic analysis was also performed in three cases. The atypical lymphoid cells consisted of activated helper T cells; four of the seven patients had lesions with a detectable clonal T-cell population. A peripheral T-cell lymphoma developed in one patient before the emergence of a genotypically different LyP T-cell clone. Cytogenetic studies were abnormal in one case of LyP and normal in another, whereas the karyotype of the lymphoma was abnormal. LyP is a preneoplastic proliferation of activated helper T cells, which is often clonal and may regress and expand with the development of new LyP clones or lymphoma.