Necrotizing eosinophilic folliculitis as a manifestation of the atopic diathesis

Eosinophilic folliculitis (EF) is an idiopathic eruption of sterile pustules and papules involving the trunk, face, and extremities, associated in many cases with human immunodeficiency virus (HIV) infection. The classic histopathology is one of follicular-based, eosinophilic spongiosis with variable microabscess formation. We describe nine HIV-negative patients who manifested a novel form of pustular EF in the setting of atopy.

Paraffin sections of skin biopsies from ten patients, stained with hematoxylin and eosin and special preparations to evaluate for microbial pathogens, were examined. Detailed clinical histories and serologic studies were obtained.

Among the clinical presentations in seven men, two women, and one girl (age range, 11-62 years) were ulcerative and/or nodular plaques mainly on the face and/or extremities, sometimes in an annular configuration. The clinical considerations included deep mycotic infection, ulcerative herpes, systemic vasculitis, Mucha Haberman disease, and pyoderma gangrenosum. All patients had a personal and/or family history of atopy. Co-existent medical illnesses included psoriasis, lupus erythematosus, and lymphoproliferative disease. One patient was on a calcium channel blocker, one on multiple antidepressants, and two on antihistamines, all of which are associated with immune dysregulation. All skin biopsies showed variable intra- follicular eosinophilic microabscesses, follicular necrosis, folliculocentric necrotizing eosinophilic vasculitis, marked degeneration of connective tissue fiber elements, and striking tissue eosinophilia, including flame figure formation and dermal eosinophilic abscesses. Apart from commensals, such as Pityrosporum and Demodex, microbial pathogens were not identified.

The presentations differed from conventional EF by virtue of a strong association with atopy and by the presence of ulceration, nodule formation, follicular and dermal necrosis, and eosinophilic vasculitis. We propose the term "necrotizing eosinophilic folliculitis," and suggest that the basis of this novel form of EF is an unrepressed T-helper lymphocyte type 2 (Th2)-dominant response to various epicutaneous stimuli in patients with atopy, the prototypic immune dysregulatory state associated with a Th2-dominant cytokine milieu.