Folliculitis Clinical Presentation

The folliculitis patient typically reports an acute onset of papules and pustules associated with pruritus or mild discomfort.

Patients with deep folliculitis usually experience more pain and may have suppurative drainage. Persistent or recurrent lesions may result in scarring and permanent hair loss.

The papulopustular eruption secondary to EGF-R inhibitors typically occurs within the first 2 weeks of the initiation of therapy and can be associated with pruritus, pain, and desquamation.

Patients with superficial folliculitis usually present with multiple small papules and pustules on an erythematous base that are pierced by a central hair, although the hair may not always be visualized. Deeper lesions manifest as erythematous, often fluctuant, nodules. Sometimes, a patterned folliculitis occurs in areas that were shaved or occluded. Any hair-bearing site can be affected, but the sites most often involved are the face, scalp, thighs, axilla, and inguinal area.

Folliculitis has been traditionally divided into superficial and deep forms; however, most superficial forms can evolve into the deep form. The most common superficial form of infectious folliculitis is known as impetigo of Bockhart or barbers itch and is caused by Staphylococcus aureus, such as the infection shown in the image below . The lesions are seen in the bearded area, often on the upper lip near the nose, as erythematous follicular-based papules or pustules that may rupture and leave a yellow crust. The pustule is often pierced by a hair that is easily extracted from the follicle. This form of folliculitis occurs more commonly in carriers of nasal staphylococci. Another type of superficial folliculitis caused by staphylococci is a sty, which only differs from typical folliculitis in that it occurs on the eyelid.

When involvement of the follicle is more extensive, a follicular-centered dermal abscess results. When the condition occurs on the face, it is referred to as sycosis barbae (vulgaris), but if it occurs elsewhere, it is referred to as a furuncle or boil. A confluence of several furuncles results in a carbuncle.^[6]

Tinea barbae is an uncommon form of superficial folliculitis that clinically resembles its bacterial counterpart; however, it is caused by a superficial infection by various zoophilic dermatophytes. This superficial fungal folliculitis is most commonly seen in male farmers and typically affects one side of the face in the submaxillary region or chin. Patients with more extensive involvement of the follicle or those who experience an exaggerated hypersensitivity reaction to the dermatophyte infection present with enlarged, boggy purulent plaques, called kerions, in the site of the prior superficial infection. Another deep fungal folliculitis occurs on the legs of women who shave, and this is called Majocchi granuloma.

Gram-negative folliculitis primarily occurs in patients on long-term antibiotic therapy, often antibiotics given for the treatment of acne. This type of folliculitis arises from disequilibrium of the normal skin bacteria in favor of gram-negative organisms such as Enterobacter, Klebsiella, Escherichia, Serratia, and Proteus species. These lesions manifest as multiple small pustules that are most pronounced in the perinasal region and can spread to the chin and cheeks.

Pseudomonal folliculitis is another gram-negative folliculitis and is also known as hot tub (spa) folliculitis and wet suit folliculitis (see the images below). It appears 8-48 hours after exposure to contaminated water or wet suits as erythematous follicular-based papules and pustules that are most concentrated in areas occluded by swimwear. This form of folliculitis may be associated with systemic findings such as fever, headache, sore throat, malaise, or gastrointestinal distress, but it is a self-limited condition that resolves in 7-14 days. Another similar condition is hot hand-foot syndrome, which occurs in a similar clinical situation but eventuates in painful erythematous nodules and papules on the palms and soles rather than folliculitis.^[7]

Pityrosporum folliculitis is typically seen in young adults, with a slight female predominance, as intensively pruritic small uniform papules and pustules on the back, chest, and shoulders. It occurs more often in warm, humid climates and may be more frequent in immunocompromised patients or in patients on long-term antibiotics. This eruption is due to follicular infection by Malassezia furfur, which is a lipophilic yeast.

An unusual cause of folliculitis occurs as a result of either overgrowth of Demodex mites or an acquired hypersensitivity to the mite. This form of folliculitis manifests with a more diffuse background erythema, in addition to the follicular-centered papules and pustules.^[8]

An uncommon form of folliculitis is due to an infection with herpes viruses. This form of folliculitis can be caused by an infection by herpes simplex viruses 1 and 2 and is found in areas adjacent to a primary cold sore. It is spread by shaving. These lesions appear as grouped or scattered vesicles.^{[9, 10]}

Varicella-zoster virus may also cause a primarily follicular-based infection. These patients present with erythematous plaques in a dermatomal distribution; however, vesicles do not typically occur. Biopsy is often required to confirm the diagnosis.^[10]

Folliculitis can also have a noninfectious etiology caused by follicular trauma or occlusion or may simply be idiopathic. For example, pseudofolliculitis barbae, also known as shaving or razor bumps, occurs primarily in the bearded area of African American males or other racial groups with thick, coarse, curly hair. This condition is not a folliculitis per se, but rather a perifolliculitis that arises as a result of the hair reentering the skin adjacent to its exit point from the follicle. The hair then acts as a foreign body and incites inflammation. The inflammation can spontaneously resolve if the hair is extracted or it can become associated with a chronic foreign body granulomatous reaction and may result in scarring.

Acne keloidalis nuchae is a similar condition that arises on the neck and occipital region of the scalp, but this condition is both a folliculitis and perifolliculitis and has greater potential for scarring.

Acute generalized exanthematous pustulosis and anticonvulsant hypersensitivity syndrome both manifest as an acute onset of a discrete pustular eruption arising shortly after beginning therapy with various medications. Although the eruption that occurs in acute generalized exanthematous pustulosis is often differentiated from anticonvulsant hypersensitivity syndrome by having nonfollicular-based pustules, either condition can have follicular or nonfollicular-based pustules.

Papulopustular drug eruption due to EGF-R is a relatively new entity and consists of a follicular eruption on the face, chest, and upper back that occurs approximately 2 weeks after initiation of chemotherapy. It is seen in up to 90% of patients taking EGF-R inhibitors, and its presence correlates to a positive response to chemotherapy.^{[1, 2]}

The last noninfectious folliculitis to be discussed is eosinophilic folliculitis. It manifests as intensely pruritic pustules and can occur in at least 3 different clinical situations. The first is the original description of eosinophilic folliculitis, also know as Ofuji disease. It arises in Japanese males at an average age of 30 years. The lesions initially begin as discrete papules and pustules that eventually coalesce to form circinate plaques composed of a peripheral rim of pustules with central clearing. These lesions appear cyclically on the face, back, and extensor surfaces of the arms and spontaneously resolve in 7-10 days. Often, peripheral eosinophilia is present.^[5]

A second form of eosinophilic folliculitis arises in patients with AIDS and other conditions that result in immunosuppression.^[11] This form is seen most often in adult males with a CD4⁺ count of less than 300 cells/μL. It is persistent and does not form an annular pattern. The lesions tend to favor the face, scalp, and upper trunk.^[12]

The last form of eosinophilic folliculitis occurs in infants, usually within the first 24 hours to first few weeks of life. It is more common in male infants and usually is self-limited; however, as in Ofuji disease, it may follow a cyclic course lasting months to years. The lesions primarily affect the scalp and eyebrows. This form may also be associated with peripheral eosinophilia.

The causes of folliculitis are multiple and include infection, friction and other causes of follicular trauma, excessive perspiration, and occlusion; however, many cases remain idiopathic. Patients who have a reduced immune status, prior skin injury, or dermatoses or those who are obese may be more at risk.