Eosinophilic pustular folliculitis is a dermatological condition, that involves the formation of pustules in the hair follicles, due to an infiltration of the latter by eosinophils, without the participation of bacteria. It is known to occur and persist in immunosuppressed patients.
Eosinophilic pustular folliculitis leads to the development of pustules and papules, caused by an eosinophilic infiltration of hair follicles. Erythema often accompanies the papules and pustules, which mainly appear on the face, in the vast majority of affected patients, and also on the back, upper extremities in the extensor region, neck, and shoulders. Scarring may also occur.
The condition has been strongly associated with certain patient groups, in whom it tends to appear in a more acute way and persist longer. These groups are mainly HIV affected patients and cancer patients, especially those suffering from a hematological malignancy  . It also tends to develop in the post-chemotherapy period . Abrasions due to scratching, very extensive erythema and plaques, alongside edematous and erythematous regions (urticaria) are often observed in HIV patients. Individuals affected by eosinophilic pustular folliculitis report an intense itch but constitutional symptoms have not been associated with the condition. Irritability and mild fatigue are the sole non-dermatologic symptoms that have been documented.
The papules and pustules are relatively small, approximately 3mm in diameter and tend to be more localized than generalized. The palms or mucosa do not constitute frequent sites of pustular development . The lesions are expected to self-heal and re-emerge after a period of time, as this is the typical clinical course of the disorder. Ultimately, the papulopustular lesions converge, forming extensive plaques whose center is observed as a healing spot, whereas the peripheral circle expands; lesions may continue to develop anew in these plaques .
Eosinophilic pustular folliculitis can also occur in infancy. In this case, the region where papules and pustules are typically expected to develop, is the scalp, in contradistinction to the torso or upper extremities.
The workup involved in a case suspected of eosinophilic pustular folliculitis includes a complete blood count (CBC), immunoelectrophoresis and a histological analysis of a sample harvested from a lesion, preferably a non-excoriated one.
Affected patients that also suffer from an HIV infection tend to exhibit marked leukopenia, with CD4 levels being less than 250 cells/mL . CBC results will also illustrate eosinophilia, elevated IgE levels and diminished IgG3 and IgA levels .
Cultures carried out on the lesion sample that is harvested are expected to reveal no pathogens, since the follicular infiltration is de novo sterile. With reference to the histological characteristics of eosinophilic pustular folliculitis, the following are expected: