Immunophenotyping and viral studies in pityriasis lichenoides et varioliformis acuta lesions.

ABSTRACT

BACKGROUND: The underlying pathogenesis of pityriasis lichenoides et varioliformis acuta (PLEVA) remains unclear, although immunologic injury and viral etiology have been suggested. OBJECTIVE: To evaluate and expand the immunophenotype of PLEVA and to search for possible viral pathogens. METHODS: Formalin-fixed, paraffin-embedded specimens of 20 patients with PLEVA and 9 patients with common inflammatory dermatoses (ID) were studied for immunophenotyping and for human herpesvirus (HHV) 1 and 2, cytomegalovirus (CMV), HHV-8, parvovirus B19, and Epstein-Barr virus (EBV) immunohistochemistry. The presence of HHV-6, HHV-7, and enteroviruses was assayed molecularly. RESULTS: The numbers of CD8+ T cells and T-cell intracellular antigen-1 (TIA-1)+ cells were statistically significantly higher in PLEVA compared to the ID group. Immunohistochemistry for human HHV-1 and HHV-2, CMV and HHV-8, parvovirus B19, and in situ hybridization for EBV were all negative. There was molecular evidence for HHV-7 in only one PLEVA case (5%). Molecular studies for HHV-6 and enterovirus involvement were negative in all the PLEVA specimens. CONCLUSIONS: The predominant T-cell infiltrate in PLEVA is dominated by CD8+ cells, and by increased numbers of TIA1+ cells, which may indicate a cytotoxic T-cell damage to the epidermis. Viral presence was not detected.