Folliculitis, Pityrosporum (Malassezia Folliculitis)
Are You Confident of the Diagnosis?
• What you should be alert for in the history
Pityrosporum folliculitis is a condition in which the hair follicles of the sebaceous areas (upper trunk, shoulders, and occasionally head and neck) are infected with Pityrosporum (Malassezia) yeasts, resulting clinically in inflammatory papules and pustules.
Patients with Pityrosporum folliculitis typically present complaining of pimples or bumps, which may be pruritic, on the upper trunk and shoulders. The eruption has often been present for many months. Patients sometimes will believe they have acne on their trunk, as the two conditions can be quite similar. The severity may wax and wane, depending on activity, time of year, and other factors.
Ask whether the patient has oily skin or sweats a lot, which may predispose to Pityrosporum overgrowth. Ask about a history of immunocompromise, cancer, diabetes, or use of antibiotics or corticosteroids, as all may increase the likelihood of developing Pityrosporum folliculitis.
• Characteristic findings on physical examination
The characteristic physical findings in Pityrosporum folliculitis are symmetrically arranged monomorphic 1-3mm follicular flesh-colored to erythematous papules and pustules on the back, chest (
Monomorphic erythematous papules and pustules on the chest of a patient with Pityrosporum folliculitis.
• Expected results of diagnostic studies
The diagnosis of Pityrosporum folliculitis is usually made based on clinical findings and response to therapy. However, microscopy of material scraped from pustules can be helpful when the diagnosis is unclear. One may scrape a pustule with a #15 blade; spread the expressed material on a slide; and treat with potassium hydroxide, Swartz Lamkins, or Chlorazol black E dye before viewing by microscopy. Budding yeast are the characteristic finding. This is in contrast to tinea versicolor, also caused by Malassezia yeasts, but which shows pseudohyphal forms.
Fungal culture is seldom used in the diagnosis of Pityrosporum folliculitis, because the causative yeasts do not grow on standard fungal media. In order to diagnose Pityrosporum folliculitis by fungal culture, it is necessary to alert the microbiology laboratory of the suspected diagnosis, so that they may grow the fungus on media containing olive oil or another lipid source.
Likewise, it is not usually necessary to biopsy Pityrosporum folliculitis, but this can be helpful in confusing cases. Histopathology shows dilated follicular openings with keratin plugging, cellular debris, and a mixed inflammatory infiltrate. Special fungal stains may highlight budding yeast forms and spores within the follicle.
• Diagnosis confirmation
The differential diagnosis of Pityrosporum folliculitis includes bacterial folliculitis, eosinophilic pustular folliculitis, acne vulgaris, steroid acne, and insect bites.
Bacterial folliculitis may have a very similar appearance to Pityrosporum folliculitis, but typically affects nonsebaceous areas, such as the thighs and buttocks, rather than the upper trunk. Cultures often grow Staphylococcus bacteria and lesions usually respond to oral antibiotics.
Eosinophilic pustular folliculitis also presents with papulopustules on the upper trunk and face, but occurs in three distinct clinical settings: a classic form seen in Japanese men, a human immunodeficiency virus (HIV)-associated form, and an infantile form. Staining of smears from pustules shows eosinophils.
Acne vulgaris may be distinguished from Pityrosporum folliculitis because acne frequently affects the face as well as the upper trunk and shoulders. It is seldom pruritic. It is often polymorphic, with comedones, cysts, and nodules often present in addition to papulopustules. However, the two conditions may coexist.
Steroid acne is most often seen in the setting of systemic corticosteroid use, but also may occur with topical corticosteroids. It presents as monomorphic papules and pustules on the upper trunk. It is possible that some cases may actually represent Pityrosporum folliculitis induced by corticosteroid use or occlusive corticosteroid ointments.
Insect bites are typically scattered on the body, rather than symmetrically located on the upper trunk.
Who is at Risk for Developing this Disease?
Pityrosporum (Malassezia) species are present on an estimated 92% of the world’s population as part of normal skin flora. Their prevalence is highest in areas of high heat and humidity.
Pityrosporum folliculitis typically affects teenagers and young adults, presumably due to their relatively active sebaceous glands. Since Pityrosporum yeasts cannot grow without exogenous lipids, they use the triglycerides found in human sebum as fuel. Individuals who are immunocompromised, diabetic, or taking oral antibiotics or systemic corticosteroids are at increased risk.
What is the Cause of the Disease?
Pityrosporum folliculitis is caused by an inflammatory reaction to Malassezia yeasts, a normal component of the skin flora. In Pityrosporum folliculitis, the yeast grow in the hair follicle, using the sebum in the follicle as fuel.
Malassezia is incapable of synthesizing its own fatty acids, and uses a number of lipase enzymes to cleave host triglycerides into free fatty acids, which they then use to build their own mid-length and long-chain fatty acids. The presence of the yeast in the follicle and the chemical compounds it produces trigger inflammatory response by activating the complement system.
Inflammatory cells involved include macrophages, lymphocytes, and neutrophils. The result of the inflammation is red itchy pustules and papules.
• Pathophysiology Patients on systemic antibiotics are thought to be at higher risk for Pityrosporum folliculitis due to non-specific killing of normal bacterial skin flora, leaving a niche for Pityrosporum to overgrow. Similarly, those with diabetes, HIV, or on prednisone or other immunosuppressives may be unable to control Pityrosporum populations, leading to their overgrowth in follicles. The disorder has also been reported during pregnancy.
Systemic Implications and Complications
Pityrosporum folliculitis is common, and its diagnosis should not prompt an involved workup for systemic disease. However, it is worth querying the patient about risk factors for diabetes and immunocompromise and taking a drug history.
Topical (recommended as an adjunct to oral therapy, not as monotherapy) Ketoconazole 2% lotion: applied daily, then a 2% ketoconazole shampoo used 2-3 times weekly for maintenance
Econazole nitrate 1% cream daily
Clotrimazole 1% cream daily
Ciclopirox olamine 1% solution daily
Selenium sulfide 1% or 2.5% lotion used as a shampoo and body wash once weekly
Fluconazole 100-200mg orally daily for 2-3 weeks, and then 200mg once monthly for maintenance
Itraconazole 200mg orally daily for 7 days, and then 400mg once monthly for maintenance
Isotretinoin 1mg/kg/day for 16-20 weeks for recalcitrant cases
A small study in Korea suggested that photodynamic therapy with methyl 5-aminolevulinic acid may be a useful modality for patients with Pityrosporum folliculitis who have contraindications to medical therapies.
Optimal Therapeutic Approach for this Disease
The most important principle in treating Pityrosporum folliculitis is to eliminate predisposing factors, if possible. For example, if the patient is on oral antibiotics, discontinuation of the antibiotics may result in improvement in the folliculitis without any specific treatment.
The second principle of treating Pityrosporum folliculitis is that the condition may be chronic, and may wax and wane, depending on the season and the patient’s activity level. Therefore, implementing a maintenance regimen consisting of topical (or rarely, oral) antifungals is important for preventing relapses.
Since topical antifungals and washes do not penetrate well into the hair follicle, first-line treatment is generally with oral antifungals. Improvement is expected within 1–2 months. Given their potential hepatotoxicity, oral antifungals are contraindicated in patients with liver disease, and liver function testing is recommended for prolonged use.
Topical antifungals and shampoos may be used simultaneously to reduce overall carriage of Pityrosporum and to maintain improvement.
Oral isotretinoin in acne dosages can be considered for its antiseborrheic properties if other treatments fail or are unable to be used. This medication carries numerous potential risks, including teratogenicity, hepatotoxicity, elevation of lipids, and mood disorders.
Unusual Clinical Scenarios to Consider in Patient Management
Patients should be seen 2–3 months after starting therapy for Pityrosporum folliculitis, in order to ascertain whether the therapy has been effective and to check liver function tests if oral antifungals were used. If the patient was initially treated with only topical antifungals and has not cleared, oral antifungals should be instituted, unless contraindicated.
Maintenance therapy is with topical antifungals (ketoconazole, econazole, clotrimazole, ciclopirox olamine) and shampoos (ketoconazole, selenium sulfide) used 2–3 times weekly. Continued avoidance of precipitating factors such as oral antibiotics and corticosteroids is recommended.
Consider Pityrosporum folliculitis in patients who develop an acneiform eruption while on chemotherapy with epidermal growth factor receptor (EGFR) inhibitors. Such cases have been reported and may be expected to increase in frequency as these agents gain more widespread use.
What is the Evidence?
Ayers, K, Sweeney, SM, Wiss, K. "Pityrosporum folliculitis: diagnosis and management in 6 female adolescents with acne vulgaris". Arch Pediatr Adolesc Med. vol. 159. 2005. pp. 64-7.(In this study, all six patients, who had recalcitrant acne vulgaris and Pityrosporum folliculitis, showed marked improvement with oral and topical antifungals. Although the study was small, it demonstrates that in the setting of treatment of acne vulgaris, Pityrosporum folliculitis can require multiple doses of oral antifungals and maintenance use of topical antifungals.)
Bäck, O, Faergemann, J, Hörnqvist, R. "Pityrosporum folliculitis: a common disease of the young and middle-aged". J Am Acad Dermatol. vol. 12. 1985. pp. 56-61.(In a fifty-one-patient study, marked improvement was seen in patients receiving treatment for Pityrosporum folliculitis. Treatment approaches included selenium sulfide shampoo, topical econazole, and 50% propylene glycol in water. If treatment was not continued, at least on an intermittent basis, the patient’s condition worsened.)
Cholongitas, E, Pipili, C, Ioannidou, E. "Malassezia folliculitis presented as acneiform eruption after cetuximab administration". J Drugs Dermatol. vol. 8. 2009. pp. 274-5.
Faergemann, J. "Current treatment of cutaneous Pityrosporum and Candida-infections". Acta Derm Venereol Suppl (Stockh). vol. 121. 1986. pp. 109-16.(A succinct article, describing methods of treating Pityrosporum diseases. Suggested treatment for Pityrosporum folliculitis includes both ketoconazole and 50% propylene glycol in water.)
Gupta, AK, Batra, R, Bluhm, R, Boekhout, T, Dawson, TL. "Skin diseases associated with Malassezia species". J Am Acad Dermatol. vol. 51. 2004. pp. 785-98.(This article is a good summary of the role Malassezia plays in a variety of skin diseases, including Pityrosporum folliculitis.)
Lee, JW, Kim, BJ, Kim, MN. "Photodynamic therapy: new treatment for recalcitrant Malassezia folliculitis". Laser Surg Med. vol. 42. 2010. pp. 192-6.(This is a small study, utilizing methyl aminolevulinate photodynamic therapy; the authors acknowledge that while some improvement was noted in several patients, further study is warranted to determine if this is a worthwhile treatment for the condition.)
Levin, NA. "Beyond spaghetti and meatballs: skin diseases associated with the Malassezia yeasts". Dermatol Nurs Jan-Feb. vol. 21. 2009. pp. 7-13.(A review article describing symptoms, pathology, and treatment of Pityrosporum folliculitis and other Malessezia diseases.)
Parsad, D, Saini, R, Negi, KS. "Short-term treatment of Pityrosporum folliculitis: a double blind placebo-controlled study". J Eur Acad Dermatol Venereol. vol. 11. 1998. pp. 188-90.(In this double-blind, 27-participant study, those treated with oral doses of the broad-spectrum antifungal itraconazole exhibited marked improvement over those receiving a placebo.)
Rubenstein, RM, Malerich, SA. "Malassezia (Pityrosporum) Folliculitis". The Journal of Clinical and Aesthetic Dermatology.. vol. 7. 2014. pp. 37-41.(A case report and brief review of the literature focusing on pathophysiology and treatment of Pityrosporum folliculitis)
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