HIV-Associated Eosinophilic Folliculitis

HIV-associated eosinophilic folliculitis, also known as eosinophilic pustular folliculitis, is an extremely pruritic rash that is seen in the later stages of HIV infection.
Eosinophilic folliculitis appears to be a hypersensitivity reaction because of the large numbers of eosinophils that are seen in the skin, but no consistent association with specific allergens has been reported.
Very few patients with eosinophilic folliculitis respond to antihistamines.
HIV-infected patients have high circulating levels of interleukin 4 and 5, the cytokines that are chemotactic for eosinophils, so a seemingly allergic manifestation such as eosinophilic folliculitis may be a result of the general immunologic derangement in these patients.
Eosinophilic folliculitis has become rare since the use of HAART has decreased the number of cases of advanced HIV infection.

Clinical Manifestations ⬆ ⬇

Severe pruritus may interfere with the patient's ability to function.
Primary lesions are urticarial papules measuring 3 to 5 mm that look like insect bites (Fig. 33.16).
Pustules may be present, but they are not the predominant lesions.
In many cases, only excoriations are present because of the intense pruritus.
Patients with long-standing eosinophilic folliculitis may develop lichenification secondary to repeated scratching.

Diagnosis ⬆ ⬇

Skin biopsy shows perifollicular and follicular infiltration by eosinophils.
Occasional peripheral eosinophilia may be present.

Differential Diagnosis

Bacterial Folliculitis (see also Chapter 16: Superficial Bacterial Infections, Folliculitis, and Hidradenitis Suppurativa for a more Complete Discussion)

May be clinically indistinguishable from eosinophilic folliculitis.
Gram's stain, bacterial culture, and skin biopsy help to make the distinction.

Pityrosporum Folliculitis

May be clinically indistinguishable from eosinophilic folliculitis.
Potassium hydroxide preparation of pus shows yeast and hyphae.
Periodic acid-Schiff stain of skin biopsy specimen shows yeast and hyphae.

Arthropod Bite Reaction

Also may be clinically and histologically indistinguishable from eosinophilic folliculitis.
Lesions are less likely to be folliculocentric.
The patient's history should include possible exposure to arthropods (e.g., fleas, lice, scabies, bed bugs, and mosquitoes).

Management

Topical steroids, antihistamines, and antibiotics are usually ineffective.
Ultraviolet B phototherapy is effective. Patients should be referred to a qualified phototherapy center. In the summer, sunlight is effective.
Isotretinoin (40 mg per day) is usually effective. Treatment must be continued for at least 3 months and may need to be continued on a long-term basis. Once the lesions have resolved, an attempt to taper the dosage to the lowest effective dose should be made. Cholesterol and triglyceride levels require monitoring on a monthly basis because of the side effect of hyperlipidemia. Because the protease inhibitors also cause hyperlipidemia, patients may need to be started on a cholesterol-lowering medication concomitantly.
Itraconazole (200 mg twice daily) may be effective.

Point to Remember

Eosinophilic folliculitis, as described herein, is almost always associated with HIV infection.

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Basics ⬇

Clinical Manifestations ⬆ ⬇

Diagnosis ⬆ ⬇

Other Information ⬆