What is eosinophilic pustular folliculitis?
Eosinophilic pustular folliculitis is a recurrent skin disorder of unknown cause. It is also known as eosinophilic folliculitis and Ofuji disease. Skin biopsies of this disorder find eosinophils around hair follicles — hence its name.
There are several variants of eosinophilic pustular folliculitis. All of them present with itchy papules or pustules. Eosinophilic pustular folliculitis is rare and more often affects males than females. Variants include:
- Classic type eosinophilic pustular folliculitis — this occurs most commonly in Japan
- Eosinophilic folliculitis associated with advanced Human Immunodeficiency Virus (HIV) infection
- Infantile eosinophilic pustular folliculitis
- Cancer-associated eosinophilic pustular folliculitis
- Medication-associated eosinophilic pustular folliculitis.
What does eosinophilic pustular folliculitis look like?
Eosinophilic pustular folliculitis presents with itchy red or skin-coloured dome-shaped papules and pustules. It may look like acne or other forms of folliculitis. The papules mostly appear on the face, scalp, neck and trunk and may persist for weeks or months. Less commonly, urticarial lesions are seen (these are larger red irritable weal-like patches similar to urticaria). Palms and soles may rarely develop similar papules and pustules, but in such cases, the condition should not be called folliculitis, as there are no follicles in these areas.
Longstanding cases may develop dermatitis or a form of prurigo, presumably because of the itching and scratching.
Eosinophilic folliculitis of HIV
How is eosinophilic folliculitis diagnosed?
Skin biopsy reveals eosinophils under the skin surface and around the hair follicles and sebaceous glands (see eosinophilic folliculitis pathology). In many cases, blood tests show a mild rise in eosinophil cells and immunoglobulin-E (IgE), and reduced IgG and IgA levels.
Eosinophilic pustular folliculitis is often a feature of immunodeficiency. Eosinophilic pustular folliculitis associated with HIV infection presents when levels of CD4 lymphocyte cells drop below 300 cells/mm3, a level at which there is an increased risk of a secondary opportunistic infection. Cases of eosinophilic pustular folliculitis have also reported after bone marrow transplantation before the immune system is back to normal functioning, and in some individuals with inherited immune deficiencies.
What is the cause of eosinophilic pustular folliculitis of HIV?
The cause of eosinophilic pustular folliculitis of HIV is not known. Immunodeficiency appears to lead to increased risk of allergic-type skin diseases. There is no proof that bacterial, fungal or viral secondary infection is the cause, although some researchers have postulated overgrowth of Malassezia or Demodex (the hair follicle mite) might be involved. Another theory is that there is a change in the immune system causing eosinophils to attack the sebum produced by sebaceous gland cells.
What is the treatment for eosinophilic pustular folliculitis?
In patients with HIV, eosinophilic pustular folliculitis is likely to improve or resolve with HAART (Highly Active Anti-Retroviral Treatment), as CD4 cell counts rise above 250/mm3.
Other treatments that may be effective include:
- Indomethacin and other nonsteroidal anti-inflammatory drugs are reported effective in up to 70% of cases of eosinophilic folliculitis
- Tetracycline antibiotics
- Other antibiotics including metronidazole
- Topical steroids
- Calcineurin inhibitors such as tacrolimus ointment
- Oral antihistamines such as cetirizine
- Permethrin cream (topical insecticide)
- Nicotine patches
- Isotretinoin and acitretin.