Clinical and histopathological differential diagnosis of eosinophilic pustular folliculitis.

Eosinophilic pustular folliculitis (EPF) is an inflammatory disease characterized by repeated pruritic follicular papules and pustules arranged in arcuate plaques, and folliculotropic infiltration of eosinophils. The diagnosis of EPF is occasionally difficult and problematic because EPF may share the clinical appearance and histological findings with other diseases. Moreover, EPF has several clinical subtypes, including the classical type, infantile type and immunosuppression-associated type. Because the therapies of EPF are relatively specific as compared to eczematous disorders, accurate diagnosis is essential for the management of EPF. Clinical differential diagnoses include tinea, acne, rosacea, eczematous dermatitis, granuloma faciale, autoimmune annular erythema, infestations and pustular dermatosis. Histologically, cutaneous diseases with eosinophilic infiltrates can be differentially diagnosed. Follicular mucinosis, mycosis fungoides and other cutaneous T-cell lymphomas are the most important differential diagnoses both clinically and histopathologically. It should be kept in mind particularly that the initial lesions of cutaneous T-cell lymphoma resemble EPF.