Pityriasis lichenoides et varioliformis acuta with numerous CD30(+) cells: a variant mimicking lymphomatoid papulosis and other cutaneous lymphomas. A clinicopathologic, immunohistochemical, and molecular biological study of 13 cases.

Pityriasis lichenoides comprises a clinicopathologic spectrum of cutaneous inflammatory disorders, with the 2 most common variants being pityriasis lichenoides et varioliformis acuta (PLEVA) and pityriasis lichenoides chronica. The aim of the study was to describe 13 cases of a unique PLEVA variant characterized in the conspicuous CD30 component and thus mimicking lymphomatoid papulosis (LyP), a condition currently classified in the spectrum of CD30 lymphoproliferative disorders. The cohort included 10 female and 3 male patients whose ages at diagnosis ranged from 7 to 89 years (mean 41 y; median 39 y). The clinical manifestation was that of PLEVA, with small erythematous macules quickly evolving into necrotic papules. No waxing and waning was seen on follow-up in any of the cases. Histopathologically, typical features of PLEVA were present, but an unusual finding was occurrence of a considerable number of CD30 small lymphocytes as detected immunohistochemically. Over half of the cases also displayed a large number of CD8 cells and showed coexpression of CD8 and CD30 in the intraepidermal and dermal component of the infiltrate. Of the 11 cases of PLEVA studied for T-cell receptor gene rearrangement, 6 evidenced a monoclonal T-cell population, and 5 were polyclonal. Parvovirus B19 (PVB19) DNA was identified in 4 of 10 cases investigated, and positive serology was observed for PVB19 in 2 patients, altogether suggesting that PVB19 is pathogenetically linked to PLEVA at least in a subset of cases. The presence of CD30 lymphocytes and CD8 lymphocytes would be consistent with an inflammatory antiviral response, as CD30, even atypically appearing lymphoid cells have been identified in some viral skin diseases. The main significance of the PLEVA variant is, however, its potential confusion with LyP or some cytotoxic lymphomas. Admittedly, the CD30 PLEVA variant described herein and LyP show considerable overlap if one takes into account all known variations of the 2 conditions recognized in recent years, thus suggesting that LyP and PLEVA may be much more biologically closely related entities than currently thought or can even occur on a clinicopathologic spectrum.