Pruritic papular eruption and eosinophilic folliculitis associated with human immunodeficiency virus (HIV) infection: a histopathological and immunohistochemical comparative study.

BACKGROUND: Among the papular-pruriginous dermatoses related to human immunodeficiency (HIV) infection, two entities remain poorly differentiated leading to confusion in their diagnosis: HIV-related pruritic papular eruption (HIV-PPE or prurigo) and eosinophilic folliculitis (HIV-EF).

OBJECTIVE: To establish histopathological and immunohistochemical parameters to differentiate between two conditions associated with HIV infection, the pruritic papular eruption (HIV-PPE) and eosinophilic folliculitis (HIV-EF).

METHODS: Clinically typical HIV-PPE (18 cases) and HIV-EF (10 cases) cases were compared with each other in terms of the following topics: clinical and laboratory features (gender, age, CD4+ cell and eosinophil count), histopathological features (hematoxylin-eosin and toluidine blue staining) and immunohistochemical features (anti-CD1a, anti-CD4, anti-CD7, anti-CD8, anti-CD15, anti-CD20, anti-CD30, anti-CD68/macrophage and anti-S-100 reactions).

RESULTS: Among the HIV-EF patients, we found an intense perivascular and diffuse inflammatory infiltration compared with those patients with HIV-PPE. The tissue mast cell count by toluidine staining was higher in the HIV-EF patients, who also presented higher expression levels of CD15 (for eosinophils), CD4 (T helper), and CD7 (pan-T lymphocytes) than the HIV-PPE patients.

LIMITATIONS: Only quantitative differences and not qualitative differences were found.

CONCLUSIONS: These data indicate that HIV-related PPE and EF could possibly be differentiated by histopathological and immunohistochemical findings in addition to clinical characteristics. In fact, these two inflammatory manifestations could be within the spectrum of the same disease because only quantitative, and not qualitative, differences were found.