Seborrheic dermatitis (SD) is a well-known, chronic and relapsing skin disease. But the roles of Malassezia spp. in the pathogenesis of SD are still unclear due to the lack of direct evidence for the existence of hyphae within affected skin tissues. 

A recent study elucidated if Malassezia mycelium contributes to the onset and development of SD and if Malassezia mycelium correlates with the clinical severity of SD patients. The study detected Malassezia hyphae in patients with SD using potassium hydroxide (KOH) and calcofluor white (CFW) staining. It performed fluorescent microscopy for analyzing fungal cell walls and morphological characteristics of Malassezia under CFW staining.

 This study demonstrated:

• A positive correlation of Malassezia hyphae with the clinical severity of SD patients.
• All the patients responded well to antifungal treatment.
• No significant difference in species dominance across the variant groups. 

However, the exact molecular mechanisms of Malassezia spp. affecting SD needs further research. 

The findings of this study indicate that Malassezia spp. in the hyphal stage is restricted to SD patients compared with healthy controls, suggesting the presence of Malassezia hyphae in contributing to the pathogenesis of SD. The results highlight the importance of antifungal therapy for treating patients with SD.

Source: Li J, Feng Y, Liu C, et al. Presence of Malassezia hyphae is correlated with pathogenesis of seborrheic dermatitis. Microbiol Spectr. 2022;10(1):e0116921.