Clinical Mycology: Direct Examination Series: Candida Malassezia [Hot Topic]
Fungus Malassezia on SDA, saline and LPCB mount showing yeast cells and hyphae
“Fungal Skin Infection of Many Colors” (Tinea Versicolor) | Pathogenesis, Symptoms and Treatment
Seborrheic Dermatitis, Psoriasis and Impetigo in Children – Pediatrics | Lecturio
NAME(S) Seborrhoeic dermatitis; dandruff; cradle cap (in babies)
DISEASE Characterised by excess scaling of the edge of the scalp, face and anterior chest associated with an inflammatory component. The relative contribution of a cell-mediated response (or hypersensitivity) to yeast colonisation of the skin versus ‘simple’ infection of the keratin layer of the skin is poorly understood. Dandruff (or its equivalent in babies, cradle cap) is characterised by excessive scaling but minimal inflammation, and is largely a cosmetic problem.
FUNGI Malassezia spp. (Pityrosporum spp.). Of these M. furfur, M. globosa and M. sympodialis are pathogenic, M. pachydermatis is acquired from animals (especially dogs) and other species are rare or only found on normal skin.
PREVALENCE Rare in children after infancy, affects 3-5% of the world’s population or 200-350 million adults
RISK FACTORS Incidence is 18-80% in HIV-infected patients, and tends to worsen as the immune deficit progresses. More common in Parkinson’s disease and after a stroke.
DIAGNOSIS Clinical diagnosis, without laboratory confirmation
TREATMENT Topical imidazole treatments, often with a low potency topical steroid in a combination ointment. Dandruff is usually treated with ketoconazole containing shampoo. Rarely oral azole therapy is required.
OUTCOMES Cradle cap remits as the baby grows. Seborrhoeic dermatitis and dandruff tend to relapse, and often require ongoing treatment
NAME(S) Pityriasis versicolor (tinea versicolor)
DISEASE Superficial skin infection of the upper trunk, usually without an inflammatory component or scaling. Depigmentation, like rain drops, or excess pigmentation over the chest or upper back is typical, especially after sun exposure
FUNGI Malassezia furfur (Pityrosporum ovale) and other related species
PREVALENCE Common, especially in tropical and subtropical regions where up to 50% of the adult population may be affected. More obvious and perhaps more common in the summer months in temperate climates. Most common between ages of 20 and 40
RISK FACTORS Possibly genetic predisposition as family members not living together are more frequently affected
DIAGNOSIS Microscopy showing budding yeasts cells from the affected area
TREATMENT There are several topical treatments available containing sulfide selenium, propylene glycol and azole antifungals. Extensive cases sometimes require oral azole treatment with ketoconazole or itraconazole
OUTCOMES Rates of recurrence are very high. In some cases prophylactic itraconazole (200mg one day per month x 6 months) has been used with a response of 88% at the end of the study