Abstract: Objective To investigate the relationship between fungi, especially Malassezia furfur and psoriasis. Methods The skin scale from scalps, nails, backs and extremities of 82 psoriatic patients and 40 healthy controls were collected and cultured on three media for isolation. Eight strains of M.furfur from psoriatic lesions and four strains from controls were analysed by flow cytometry. Results (1)It was found that the isolation rates of fungi were significantly higher in psoriatic group than those in controls (P<0.05). The isolation rates of the lesions were significantly higher than those of the uninvolved skin in psoriatic patients (P<0.01).(2)Fifty nine strains of M.furfur in psoriatic group and 9 strains in controls were cultured and the difference of isolation rate was significant. (3)The ratio of cells in S stage and proliferative index of isolated M.furfur were significantly lower in psoriatic group than those in controls. Conclusion The results indicate that fungi, especially M.furfur, are more frequently isolated in the lesions and uninvolved skin of psoriatic patients than those in healthy controls. It is suggested that fungi might play a role in the pathogenesis of psoriasis.

Key words: Psoriasis, Fungi, Malassezia