Pityrosporum (Malassezia) folliculitis: symptoms and treatment

A hair follicle is the small pocket in the skin from which a hair grows. Folliculitis is inflammation of these follicles. Patient.info describes folliculitis as a relatively common condition in primary care with several possible causes, including bacteria, fungi, viruses, physical irritation and chemical irritation.

Pityrosporum folliculitis is the older name for a fungal type, now generally called Malassezia folliculitis. Malassezia is a type of yeast that lives on the skin of most people and usually does no harm. DermNet explains that in this condition the yeasts are seen within the hair follicle, and that it is a recognised skin disease associated with Malassezia yeasts.

In everyday language, it is sometimes called fungal acne. That label is understandable because the spots can look like acne, but the underlying problem is different, and the treatment is different too. Acne treatments and antibiotics do not usually help and, as DermNet notes, antibiotic use is itself listed among the risk factors.

DermNet links it to warm, humid conditions, sweating, oily skin and occlusion.

DermNet describes small, uniform, itchy papules and pustules, particularly on the upper back and chest, with other sites including the forehead and hairline, chin, neck and the outer surfaces of the upper arms. Because all the spots tend to look alike, it is called a monomorphic eruption.

The itch is a helpful clue. Patient.info describes an itchy acneiform eruption, and DermNet says the spots are itchy. A person with typical acne usually has a mixture of blackheads, whiteheads and larger inflamed spots, whereas pityrosporum folliculitis tends to be a crop of similar small bumps.

• Small, similar-looking bumps or pustules, often centred on hair follicles.

• Itching, which may be marked.

• Most often on the upper back, chest and shoulders, but also the neck, upper arms, chin or hairline.

• No blackheads or whiteheads, which helps to distinguish it from acne.

• A tendency to flare in hot weather, after sweating or after antibiotic or steroid treatment.

DermNet says Malassezia folliculitis is most commonly seen in adolescent and young adult males, and Patient.info says it affects younger patients. The risk factors DermNet lists are a hot humid climate, high sebum production, hyperhidrosis (excessive sweating), occlusion from emollients and sunscreens, antibiotic use and immunosuppression, including topical and oral steroid use and HIV.

Recurrent or widespread disease in a person with no obvious trigger can be a reason for a clinician to look for an underlying cause, for example diabetes or a medicine effect, though many people have no underlying condition. Patient.info lists poorly controlled diabetes and reduced immunity among risk factors for folliculitis in general.

DermNet says that clinical examination raises the diagnosis, and that laboratory tests on a skin scraping, tape stripping, swab or biopsy can confirm the presence of yeasts, because bacterial folliculitis and steroid acne can be clinically similar. A potassium hydroxide preparation of skin scrapings may show budding yeasts. Culture needs special media, so it is not routinely performed.

DermNet notes that diagnosis is often delayed because of the resemblance to acne vulgaris, steroid acne and bacterial folliculitis. If you have itchy, uniform spots that have not improved with acne treatments or with antibiotics, it is reasonable to tell your GP or pharmacist about this possibility. The NHS describes acne as usually affecting the face, chest and back, which is why the two are so easily confused.

DermNet advises addressing any predisposing factors at the outset, as Malassezia folliculitis has a tendency to recur. It says topical treatments such as selenium sulfide shampoo, econazole solution and topical ketoconazole are effective in the majority of cases but may require a longer course than systemic agents, and that ongoing weekly application may be useful as maintenance therapy.

Oral treatment may be more effective than topical, although results of clinical trials have not consistently shown this. DermNet says fluconazole is used more commonly than itraconazole because of its superior side-effect profile, and that isotretinoin and photodynamic therapy have been used with some success in small case series of resistant disease. Oral antifungal medicines are prescription-only and need a clinician to check for interactions with other medicines.

Practical measures follow from the risk factors: avoiding unnecessary heavy occlusive products on affected skin, and reviewing the need for ongoing antibiotics or steroids with the prescriber rather than stopping them on your own. Your GP or a dermatologist can advise on which treatments are suitable.

The condition is not dangerous, but it can be persistent and irritating. DermNet says recurrence is common even after successful treatment, that long-term prophylaxis with topical agents may be considered in people at high risk or with multiple recurrences, and that periodic re-evaluation of predisposing factors is recommended.

Because it can coexist with acne, some people need both conditions treated. If you are not improving, ask for a review rather than repeating the same treatment; a different diagnosis, such as bacterial folliculitis, steroid acne or another skin condition, may be more likely.