Therapeutics in Dermatology
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Eosinophilic folliculitis

21 February 2013, by SOARES-DE-ALMEIDA L. & FERNANDES S.


Eosinophilic folliculitis is a noninfectious follicular disorder mediated by eosinophils [1, 2]. 2 It could be considered as a histological cutaneous reaction pattern that may be found in a heterogeneous group of disorders. Its etiology is unknown, although it has been suggested that a T-helper type 2 (Th2) shift may be a possible pathogenic mechanism for the infiltration of eosinophils [2, 3]. With unknown prevalence, eosinophilic folliculitis is more common in male patients [2]. Peripheral blood eosinophilia is variable [2].

Itchy sterile follicular papules and pustules are the key clinical features, with some differences according to the three main clinical subsets [2, 4]:

– AIDS (or immunosuppression)-associated eosinophilic folliculitis, with more persistent severely pruriginous lesions involving the upper trunk, head and neck, and proximal extremities. In HIV patients this disorder usually correlates with a low CD4 count (in particular CD4 cell counts below 300/mm3) [5-7] conversely, it may appear during HAART-induced immune restoration in some cases.

– Ofuji’s disease or Eosinophilic pustular folliculitis is a rare entity that occurs mainly in immunocompetent Japanese adult males ; cutaneous lesions have a seborrheic distribution (face, scalp), although it may also occuron the trunk and extremities; this entity presents with recurrent crops of cutaneous lesions that expand centrifugally with central clearing, leading to circinate plaques [1, 2, 4].

– Eosinophilic pustular folliculitis of infancy is an unusual, self-limiting disorder, primarily involv­ing the scalp and frequently developing secondary crusting [3, 8, 9].

Besides these three variants, some rare cases of drug-induced eosinophilic pustular folliculitis (e.g. allopurinol, carbamazepin, anti-TNFa) have also been reported [10-13].

Histologically, eosinophils predominate in the inflammatory infiltrate involving the perifollicular area and the hair follicle outer rooth sheat which displays spongiotic change [Figure 1] [2, 3]. 3 A perivascular and interstitial infiltrate with admixed lymphocytes and eosinophils is often present as well, with negative special stains for microorganisms. Ofuji’s disease and Eosinophilic pustular folliculitis of infancy are also characterized by the frequent occurrence of epidermal changes with eosinophils exocytosis and spongiosis resulting in small subcorneal or intraepidermal eosinophilic pustules [2, 8].

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