Eosinophilic Pustular Folliculitis Workup

Updated: Apr 05, 2021
  • Author: Robert A Schwartz, MD, MPH; Chief Editor: Dirk M Elston, MD  more...
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Workup

Laboratory Studies

Cytologic smears show abundant eosinophils.

In the classic form, mild-to-moderate leukocytosis and eosinophilia are often evident. The latter is seen in about one half of patients.

With HIV disease, the CD4 count is often less than 300 cells/µL.

Infants with this disorder may have an elevated serum immunoglobulin E level with reduced serum immunoglobulin G and immunoglobulin A levels and diminished neutrophil chemotactic activity.

Because childhood eosinophilic pustular folliculitis may be associated with AIDS, lymphoma, leukemia, and other hematologic diseases, a thorough systemic evaluation is indicated. [31]

Take skin swabs for microscopy and culture and scrapings for mycologic analysis when a microbial infection or superinfection is suspected.

Consider HIV- and non–HIV-related causes of immunodeficiency.

When vesicles predominate, perilesional skin may be examined with direct immunofluorescence, and serum may be evaluated with indirect immunofluorescence on healthy human skin and/or desmoglein 1/desmoglein 3 enzyme-linked immunosorbent assay to exclude pemphigus foliaceus or pemphigus vulgaris. Both of these conditions might initially be evident as pemphigus herpetiformis, thus looking like eosinophilic pustular folliculitis both clinically and histopathologically.

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Histologic Findings

Examine fresh, unexcoriated papulovesicles histologically, ideally in serial sections. Transverse sectioning may be needed if routine vertical sections give equivocal results as depicted below. Use routine hematoxylin and eosin stain as well as special stains for fungi and bacteria.

Transverse section from a 21-year-old man with eos Transverse section from a 21-year-old man with eosinophilic pustular folliculitis. A perifollicular inflammatory infiltrate containing numerous eosinophils is present (hematoxylin and eosin, original magnification X400).

Subcorneal pustules of predominately eosinophils may be evident in the epidermis and the outer root sheath of hair follicles. Hair and sebaceous gland structures may be infiltrated with eosinophils, plus a few neutrophils and mononuclear cells (see the image below).

Vertical section from a 3-year-old girl with eosin Vertical section from a 3-year-old girl with eosinophilic pustular folliculitis. A perifollicular inflammatory infiltrate containing eosinophils is present (hematoxylin and eosin, original magnification X200).

A patchy sebaceous lysis is observed in certain cases of HIV-related eosinophilic pustular folliculitis. Follicular eosinophilic abscesses are infrequently observed in HIV-associated cases of Ofuji disease. Infantile eosinophilic pustular folliculitis of the scalp may show an interfollicular dermal infiltrate with a substantial admixture of eosinophils and flame figures but not follicular spongiosis or degeneration.

Sometimes, mucin deposition can be observed in the hair follicles. Histopathologic study may reveal the coexistence of Ofuji disease and follicular mucinosis in patients with or without concomitant HIV infection. The lymphocytes in the HIV-associated type are predominately CD8+ lymphocytes.

Palmar and plantar plaques show subcorneal or intraepidermal eosinophilic abscesses and spongiosis. Small foci of acantholysis may be seen in individual cases of eosinophilic pustular folliculitis.

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