Papular pruritic eruption (PPE) is the most common cutaneous manifestation of human immunodeficiency virus (HIV) and is recognized by the World Health Organization (WHO) as a disease of HIV at clinical stage 2. PPE has a reported prevalence of 11%-46%, depending on geographic region. It is most commonly reported in African countries, Haiti, Brazil, and Thailand, and is less commonly reported in European and North American countries.

PPE is characterized by multiple, discrete, skin-colored or erythematous urticarial papules. The lesions are most commonly located on the extremities but can also be found on the trunk and face, or lesions can be generalized with sparing of mucous membranes, palms and soles, and digital web spaces. The associated pruritus may lead to excoriations, secondary infections, prurigo-like nodules, and eventual hyperpigmentation and possible scarring. PPE displays a chronic course that waxes and wanes, and new lesions may appear daily.

In a patient with known HIV, to diagnose PPE, lesions must be present for about 1 month in the absence of another identifiable cause of itching. In a patient without known HIV, PPE may be the presenting symptom of HIV infection. Studies have reported a positive predictive value (PPV) for HIV of about 82%-87%, so PPE may serve as a diagnostic clue when other forms of testing are unavailable, such as in resource-limited settings.

No clear etiology for PPE has been established, but the most commonly proposed theory is a relation to arthropod bites. PPE may be a reaction to arthropod bites, may begin as a bite that then evolves, or may be a hypersensitivity reaction to arthropod antigens that were previously tolerated. Some studies have suggested that the lesions of PPE are an immunologic manifestation related to the inversion of the normal ratio of CD4:CD8 T-cells and the normal ratio of Th1:Th2 response and cytokine profile that occurs in HIV infection and results in the inability to recognize endogenous proteins.

Related topics: HIV/AIDS-related pruritus, HIV primary infection, pruritus without rash