Papular pruritic eruption of HIV
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
L29.8 – Other pruritus
271757001 – Papular eruption
Differential Diagnosis & Pitfalls
- Immunosuppression-associated eosinophilic folliculitis (EF) is also a common cutaneous condition in HIV patients. It has been proposed to be in the same spectrum of disease as PPE or a subset of PPE as the lesions are predominantly excoriated or edematous papules. A critical distinguishing factor from PPE is the body distribution of EF. PPE is most commonly located on the extremities while EF is typically seen above the nipple line on the face, neck, upper arms, and trunk.
- Other causes of folliculitis: Pityrosporum folliculitis (typically pruritic), Demodex folliculitis, bacterial folliculitis
- Papular urticaria / arthropod bite reactions
- Prurigo nodularis