Significance of CD30 Expression by Epidermotropic T Cells in Lymphomatoid Papulosis and Lymphomatoid Pityriasis Lichenoides

Background: The T cell activation antigen CD30 is widely used to differentiate lymphomatoid papulosis (LyP) from pityriasis lichenoides. However, CD30 has recently been reported to be expressed by CD8+ cells in the epidermis and dermis of some cases of pityiasis lichenoides et varioliformis acuta (PLEVA). Methods: This observation prompted us to review our experience with cases initially diagnosed as LyP or “lymphomatoid” pityriasis lichenoides for CD30 expression by epidermotropic T cells. Results: CD30 expression by more than 20% of the epidermotropic T cells was observed in a group of 10 cases characterized clinically by self-healing papulonodules (two cases also with infiltrated plaques) and pathologically by atypical lymphocytes with cerebriform nuclei within the epidermis and dermal infiltrate. Conclusions: CD30 can be expressed by either CD4+ or CD8+ cells in cases of LyP with epidermotropic T cells (so-called mixed LyP type A/B), but three of our cases appear to be examples of lymphomatoid CD30+ PLEVA. In addition, three cases had serologic manifestations suggestive of a lupus erythematosus-like autoimmune disorder. We hypothesize that CD30+ lymphocytes with cerebriform nuclei in some cases result in accumulation of benign activated CD8+ and CD4+ T cells rather than neoplastic cells.