Malassezia folliculitis is a fungal infection of the superficial stratum corneum and hair follicles caused by malassezia, characterized by follicular papules, papulovesicles, or small pustules, more common in the neck, chest, shoulder, and back.
The disease is caused by malassezia. Malassezia is a normal parasitic fungus on the skin, and is a conditioned pathogen. Under certain conditions, such as hyperhidrosis, greasy skin, low skin immunity, and long-term large-dose use of glucocorticoids or broad-spectrum antibiotics, malassezia replicates massively in the hair follicles, and the secreted esterase can decompose lipids, producing free fatty acids, which can stimulate the hair follicles and surrounding tissues to produce inflammatory responses, thereby inducing the disease.
Signs and Symptoms
The disease occurs mostly in 16 - 40 years old adults, predominantly in males. The skin lesions are follicular, hemispherical, pinhead sized, scattered, symmetrical, shiny, red, dozens to hundreds of papules, with red halos, more common in the chest, neck, shoulders, upper arms, waist, and abdomen, without fusion, with or without small pustules or comedones. Subjective symptoms are pruritus, and blood scabs and scratch marks can be seen. Wheals, patchy erythema, or positive dermographism are present in some patients. The greasy skin may be accompanied by facial acne, tinea versicolor, hyperhidrosis, and epidermal cysts. Keloidosis can occur on the basis of folliculitis in patients with cicatricial diathesis. The onset or exacerbation follows the administration of high-dose broad-spectrum antibiotics or glucocorticoids.
Figure 1 malassezia folliculitis
Figure 2 malassezia folliculitis
In PAS staining, numerous, aggregated, 2 - 5μm in diameter, round or oval blastospores can be seen in the enlarged hair follicle cavity. Occasionally, single, clustered, or small groups of spores are visible. In HE staining, keratoderma, mononuclear cells clustered on and around the hair follicles, and dermal perivascular lymphocytes and histiocytes infiltration can be observed. Sometimes, mild neutrophil infiltration can be seen.
On the basis of clinical findings and positive fungal examinations, a diagnosis can be provided.
Malassezia folliculitis invades the deep hair follicles. Common topical antifungals are less effective, but topical antifungals containing penetrants are effective.
Topical 50% propylene glycol, imidazole or allylamine creams or solutions, and 5% - 10% sulfur ointment, as well as selenium sulfide or 2% ketoconazole lotion can be selected.
Systemic itraconazole or fluconazole can be considered if necessary.