What causes eosinophilic folliculitis (EF)?

Updated: Mar 17, 2021
  • Author: Camila K Janniger, MD; Chief Editor: Michael Stuart Bronze, MD  more...
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Although production of cytokines and chemotactic factors and expression of intercellular adhesion molecules are evidence of activation of the follicular sebaceous unit, the stimuli that provoke these changes are unknown. The cause of classic eosinophilic pustular folliculitis is unknown, although immune processes almost certainly play a key role in its pathogenesis.

Eosinophilic folliculitis may be associated with HIV infection, various drugs, and some lymphomas; it may be considered a nonspecific dermatopathologic pattern in such settings. [12] Drugs that have been associated with eosinophilic folliculitis are carbamazepine, allopurinol with or without timedium bromide, foscarnet, and various chemotherapeutic agents. [13, 14, 15, 16, 17, 18]

Many observations suggest a role for immunologic, infectious, and environmental factors.

Brenner et al described 3 cases of eosinophilic folliculitis associated with Pseudomonas infection of the hair follicles; the lesions improved with antipseudomonal treatment but recurred upon cessation of therapy. [19]

Other investigators have reported infectious associations, including dermatophyte infection, as well as infections due to larva migrans, Pityrosporum infection, retrovirus, [20] and hepatitis C virus infection. [21]

A linkage with pregnancy has been observed. [22]

In addition, eosinophilic folliculitis has been associated with various medical conditions, including lymphoma, Sézary syndrome, [23] leukemia, [24]  myelodysplastic syndrome, atopy, cutaneous angiosarcoma, and polycythemia vera. [25, 26, 27, 28, 29]

Eosinophilic folliculitis may also develop following bone marrow and solid organ transplantation. [30, 31] It may be considered a reaction related to immune dysregulation.

Eosinophilic folliculitis associated with wearing protective gear during the COVID-19 pandemic has been described.

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