Classical EPF is more common in immunocompetent individuals in Japan and has a slight male predominance with peak incidence around the age of 30. Recurrent crops of follicular papular pustules arise on normal skin and atop erythematous plaques. There is typically intense accompanying pruritus. The lesions often heal in 7-10 days and reappear every 3-4 weeks. The face and trunk are commonly affected, but other variants can affect the extremities, palms, and soles. Systemic symptoms are not usually seen.
The etiology of classic EPF remains unclear. Some evidence suggests involvement of cytokines and adhesion molecules that activate the follicular unit.
L73.8 – Other specified follicular disorders
95333004 – Eosinophilic pustular folliculitis
Differential Diagnosis & Pitfalls
- Immunosuppression-associated EPF – Discrete urticarial follicular papules with more severe pruritus refractory to indomethacin treatment in an immunosuppressed individual.
- Infancy-associated EPF – Patients are usually between 2-10 months of age with papulopustular lesions on the scalp and no annular pattern.
- Bacterial folliculitis
- Pityrosporum folliculitis
- Demodex folliculitis
- Perioral dermatitis
- Amicrobial pustulosis of the folds
- IgA pemphigus
- Subcorneal pustular dermatosis – Annular lesions with sterile pustules never affecting the face.
- Miliaria pustulosa
- Tinea faciei – Typically annular scaly plaques are seen; pustules are uncommon.
- Palmoplantar pustular psoriasis