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 [1] [2]. It also tends to develop in the post-chemotherapy period [3]. 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 [4]. 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 [5].

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 [6]. CBC results will also illustrate eosinophilia, elevated IgE levels and diminished IgG3 and IgA levels [7].

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:

• Spongiosis of the follicular epithelium
• Eosinophilic, neutrophilic, lymphocytic and mononuclear infiltration of the outer sheath of the follicle; sebaceous lysis is also observed [3] [8]
• Minor percentage of ruptured follicles
• Follicular mucinosis (possibly)
• Basophilic infiltration in cutaneous regions [9]
• If lesions are present in the soles or hands, subcorneal or intraepidermal pustules are seen

Treatment for EPF aims to reduce symptoms and prevent flare-ups. Topical corticosteroids are commonly prescribed to reduce inflammation and itching. In more severe cases, oral medications such as antihistamines or systemic corticosteroids may be used. For HIV-associated EPF, antiretroviral therapy can help manage the condition. Phototherapy, which involves exposure to ultraviolet light, may also be beneficial for some patients.

The prognosis for EPF varies depending on the type and underlying causes. Classic EPF often follows a chronic course with periods of remission and flare-ups. Infantile EPF usually resolves spontaneously as the child grows older. HIV-associated EPF may improve with effective antiretroviral treatment. While the condition can be managed, it may persist for years and require ongoing treatment to control symptoms.

The exact cause of EPF is not well understood. It is believed to involve an abnormal immune response that leads to the accumulation of eosinophils in the skin. Genetic factors, environmental triggers, and underlying health conditions such as HIV infection may contribute to the development of EPF. In some cases, medications or infections may act as triggers.

EPF is a rare condition, and its prevalence is not well documented. It can affect individuals of all ages, but certain forms are more common in specific populations. Classic EPF is more frequently seen in adults, while infantile EPF occurs in infants and young children. HIV-associated EPF is primarily observed in individuals with HIV infection.

The pathophysiology of EPF involves an inflammatory response in the hair follicles, leading to the infiltration of eosinophils. This immune response results in the formation of pustules and the characteristic symptoms of itching and redness. The exact mechanisms triggering this response are not fully understood, but it is thought to involve a combination of immune dysregulation and external factors.

Preventing EPF can be challenging due to its unclear etiology. However, managing underlying conditions such as HIV and avoiding known triggers may help reduce the risk of flare-ups. Maintaining good skin hygiene and avoiding excessive scratching can also prevent secondary infections and minimize scarring.

Eosinophilic Pustular Folliculitis is a rare skin disorder characterized by itchy, pus-filled bumps primarily affecting hair follicles. It can occur in various forms, including classic, infantile, and HIV-associated types. Diagnosis involves clinical evaluation and laboratory tests, while treatment focuses on symptom management. The condition's prognosis varies, with some forms resolving spontaneously and others requiring long-term management.

If you have been diagnosed with Eosinophilic Pustular Folliculitis, it's important to follow your healthcare provider's treatment plan to manage symptoms effectively. This may include using prescribed medications and maintaining good skin care practices. Understanding your condition and recognizing potential triggers can help you manage flare-ups and improve your quality of life.

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