Pruritic Papules on the Face and Chest

The Diagnosis: Eosinophilic Folliculitis

A shave biopsy specimen of an intact pustule on the left side of the chest was obtained. Histopathologic examination revealed follicular inflammation with copious eosinophils (Figure, A and B). Based on the histopathology and clinical presentation, a diagnosis of human immunodeficiency virus (HIV)-associated eosinophilic folliculitis (EF) was made.

A, Follicular inflammation with copious eosinophils (H&E, original magnification ×100). B, Eosinophils infiltrated the lower segment of the follicular infundibulum (H&E, original magnification ×200). C, A pigmented hair fiber and a Demodex mite in the follicular canal (H&E, original magnification ×400).

The patient was started on triamcinolone ointment 0.1% twice daily to active lesions, oral cetirizine 10 mg in the morning, and oral hydroxyzine 25 mg at bedtime. Laboratory evaluation at the time of diagnosis showed eosinophilia with a peripheral blood eosinophil count of 0.5 K/μL (reference range, 0.03–0.48 K/μL).

Human immunodeficiency virus-associated EF is a pruritic follicular eruption that occurs in HIV-positive individuals with advanced disease. Clinically, it is characterized by intermittent, urticarial, red or flesh-colored, 2- to 5-mm papules with sparse pustules involving the head, neck, arms, and upper trunk.^1,2 The cardinal clinical feature of the disorder is intense pruritus, with overlying crusts and excoriations present on physical examination.³

Patients usually have a CD4 count of less than 250 cells/mm³.^2,3 Patients with HIV can develop an exacerbation of EF in the first 3 to 6 months after initiating antiretroviral therapy. This clinical pattern is believed to be due to the reconstituted immune system and increased circulation of inflammatory cells.⁴ Peripheral eosinophilia and elevated serum IgE levels are found in 25% to 50% of patients with HIV-associated EF.^2,3

Clinically, the differential diagnosis of intensely pruritic papules with excoriations should include scabies.³ Other diagnoses to consider include opportunistic infections and papular urticaria.⁵ Acne vulgaris and Demodex folliculitis also may present with lesions similar to HIV-associated EF; however, these lesions tend not to be as intensely pruritic.^1,5

The etiology of HIV-associated EF is unknown.³ One proposed mechanism involves a hypersensitivity reaction to Pityrosporum or Demodex mite fragments, as evidenced by studies that found fragments of these microorganisms in biopsied lesions of HIV-associated EF.^3,6 In our patient's histopathology, it was noted that the afflicted hair follicle held a single Demodex mite (Figure, C).

The histopathology is characterized by a perifollicular inflammatory infiltrate of eosinophils and CD8+ lymphocytes with areas of sebaceous lysis.^3,6 Spongiosis of the follicular epithelium is seen in early lesions of HIV-associated EF.⁶

The first-line treatment of HIV-associated EF includes antiretroviral therapy with topical steroids and antihistamines. Human immunodeficiency virus-associated EF improves as CD4 helper T-cell counts rise above 250 cells/mm³ with continued antiretroviral therapy, though it initially can cause a flare of the condition.⁴ High-potency steroids and antihistamines are added during this period to treat the severe pruritus.^1,7 In particular, daily cetirizine has been shown to be effective, which may be due to its ability to block eosinophil migration in addition to H1-receptor antagonist properties.^3,7

Various alternative therapies have been described in case reports and case series; however, there have been no controlled studies comparing therapies. Phototherapy with UVB light 3 times weekly for 3 to 6 weeks has been effective and curative in recalcitrant cases.⁷ Other frequently used treatments include oral metronidazole, oral itraconazole, and permethrin cream 5%. The effectiveness of the latter 2 treatments is believed to be related to the proposed role of Pityrosporum and Demodex in the pathogenesis.³

Acknowledgment
The authors thank Garth Fraga, MD (Kansas City, Kansas), for his help compiling the histopathological images and their diagnostic descriptions.