What is eosinophilic folliculitis?
Eosinophilic folliculitis is a recurrent skin disorder of unknown cause. It is also known as "eosinophilic pustular folliculitis" or "Ofuji disease". Skin biopsies of this disorder find eosinophils (a type of immune cell) around hair follicles – hence its name.
There are several variants of eosinophilic folliculitis.
All of them present with itchy papules (bumps) or pustules. Eosinophilic folliculitis is rare and more often affects males than females. Variants include:
- Classic type – this occurs most commonly in Japan
- Eosinophilic folliculitis associated with advanced Human Immunodeficiency Virus (HIV) infection
- Infantile eosinophilic folliculitis
- Cancer-associated eosinophilic folliculitis
- Medication-associated eosinophilic folliculitis
What does eosinophilic folliculitis look like?
Eosinophilic folliculitis presents with red or skin-coloured dome shaped papules (bumps) and pustules. It may look rather 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 wheal-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.
How is eosinophilic folliculitis diagnosed?
Skin biopsy reveals eosinophils under the skin surface and around the hair follicles and sebaceous glands. In many cases blood tests show a mild rise in eosinophil cells and immunoglobulin-E (IgE), and reduced IgG and IgA levels.
Eosinophilic folliculitis is often a feature of immunodeficiency. Eosinophilic 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 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 folliculitis of HIV?
The cause of eosinophilic 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 (oils produced in the skin) of sebaceous gland cells.
What is the treatment for eosinophilic folliculitis?
In patients with HIV, eosinophilic 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.