Scalp Fungus

Antifungal treatment of scalp psoriasis with ketoconazole produces marked improvement correlated with reduction in Malassezia cell counts. Malassezia constitutes approximately 46% of healthy scalp flora, rising to 74% in dandruff patients, with scalp histamine levels more than double those of healthy controls. Although Malassezia accounts for only 5–10% of total genomic material on human skin, its cells are up to 8 times larger than bacterial cells, making its functional biomass disproportionately large. Malassezia is dimorphic, existing in both yeast and mycelial phases; before this was understood, the two forms were classified as separate organisms named Malassezia and Pityrosporum. Malassezia causes inflammation by secreting lipases that elevate pro-inflammatory free fatty acids, triggering arachidonic acid release via phospholipase, generating reactive oxygen species, and producing toxic secondary metabolites. The organism responsible for dandruff is a specific fungus that feeds exclusively on lipids in the sebaceous glands of the scalp. The scalp fungus thrives precisely when sebum production is elevated, making excess sebum its direct growth substrate. The IL-23/IL-17 axis i…