[Scytalidium dimidiatum pseudodermatophyte, agent of superficial mycoses and phaehyphomycosis]

Scytalidium dimidiatum is a fungus found mainly in tropical and subtropical zones. Infection can cause a benign disease closely resembling dermatophytosis. In immunocompromised hosts, Scytalidium dimidiatum can also lead to phaehyphomycosis. Although awareness of these hyphae remains limited in developed countries, their incidence is growing due to increasing immigration and tourism. The rising incidence is well illustrated by three patients who presented onyxis and squamous-like manifestations on the arch of the foot upon returning from trips overseas and in whom various treatments were unsuccessful. In all three cases, culture in non-selective Sabouraud medium identified Scytalidium dimidiatum. These findings underline the need for laboratory testing before undertaking local or systemic treatment of onyxis especially since this pathogen can cause systemic disease. Study of ribosome genes showed that Scytalidium hyalinum is an homologous unpigmented mutant form of Scytalidium dimidatum. No antifungal agent has been effective for management of superficial manifestations and prevention depends mainly on the use of appropriate footwear in endemic areas.