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A 32-year-old HIV-infected woman from Uganda with a recent CD4 count of 400 cells/µL presents with a diffuse, pruritic rash that has persisted for 3-4 years.
The patient was diagnosed with HIV infection approximately 3 1/2 years ago, and started taking a 3-drug regimen (zidovudine, lamivudine, abacavir) shortly thereafter. She has been on antiretroviral therapy (ART) for 3 years, with a good CD4 response (the nadir CD4 count was 40 cells/µL). The appearance of her rash predates the initiation of ART.
The rash has been present mostly on her arms and legs. It was extremely pruritic initially, though itching became less severe after she started taking ART. The patient considers the rash disfiguring. She has no other complaints and is taking her medications regularly, as indicated by appropriate pill counts at her clinic visits. She denies taking any new medications. No other members of her family have similar symptoms. She reports no unusual environmental exposures.
General: Examination of the skin revealed multiple scattered hyperpigmented macules, some with central hypopigmentation, and rare papules, present from head to feet, but most prominently over both lower extremities. The distribution was not follicular. (See figures.)
Laboratory tests: None available, other than CD4 count.
Differential diagnosis: Possible causes of this presentation included pruritic papular eruption (PPE), prurigo nodularis, lichen simplex chronicus, eosinophilic folliculitis, drug eruption, and scabies.
Probable diagnosis: A diagnostic biopsy had not been performed. PPE with postinflammatory hyperpigmentation and scarring was diagnosed clinically.
Treatment: The patient was treated with topical corticosteroids for a course of indefinite duration. This is the standard of care at the HIV clinic where she receives treatment. She was not treated with any oral medications for this condition.
Clinical course: Unknown. The patient was examined only once, although her symptoms had improved marginally in recent years after she began receiving ART and topical steroids.
Although no diagnosis could be made on the basis of tissue biopsy, the skin findings for this patient are highly consistent with pruritic papular eruption (PPE) with postinflammatory hypo- and hyperpigmentation and scarring from prior lesions. Many patients at the clinic had similar symptoms and were treated symptomatically with topical steroids and calamine lotion. The effectiveness of this treatment has not been established.
PPE typically presents as scattered papules or pustules that are <1 cm in diameter and located primarily in the extremities and the trunk, often with superficial excoriation. PPE has been well described in sub-Saharan Africa and elsewhere, with varying geographical prevalence. Reported PPE prevalence among HIV-positive patients has ranged from 18% in hospitalized patients in Zaire (1) to 33-37% in Thailand (2,3) to 46% in Haiti,(4) with few reported cases in the United States, except in areas with high mosquito prevalence such as southern Florida,(5) where a PPE prevalence of 11% has been reported.(6)
An inverse relationship between the absolute CD4 cell count and the prevalence and symptom severity of PPE has been reported. Symptoms have been found more often in patients with advanced HIV disease.(7,8) A study of 120 HIV-positive patients in Thailand found 0 cases of PPE in those with CD4 counts of >500 cells/µL.(3) In contrast, 34% of patients with CD4 counts between 200 and 499 cells/µL, and 81% of patients with CD4 counts of <200 cells/µL, showed evidence of PPE.
The clinical presentation of PPE is well described, but the underlying etiology was somewhat elusive until recently. In a 2004 study of 102 HIV-positive patients in Uganda, a majority of biopsy specimens indicated that a histology of arthropod bites was highly consistent with the development of PPE papules.(9) Specifically, most of the specimens revealed "moderately dense to dense, superficial and deep, perivascular and interstitial infiltrates of lymphocytes and many eosinophils beneath an epidermis that was slightly hyperplastic," whereas others showed a "punctum," or focal area of epidermal spongiosis surrounded by dermal infiltrates. The investigators surmised that the occurrence of PPE could represent an abnormal and exaggerated immune response to mosquito bites in individuals with low CD4 counts.
At the clinic where this patient sought care, persistent pruritus in HIV-positive patients was routinely treated with topical steroids, even though this approach has been shown to be relatively ineffective.(10) One small study of 8 patients showed partial resolution of lesions with regular ultraviolet B phototherapy,(11) though this treatment remains controversial. Additionally, the use of pentoxifylline appears promising as an effective treatment,(12) but this approach has not been studied in a randomized controlled trial.