Two cases of chromomycosis identified by molecular phylogenetic analysis

Abstract

Chromomycosis is an infection caused by dematiaceous fungi. These fungi belong to several genera with varied clinical presentations and parasitic forms. The disease is roughly classified into three types: chromoblastomycosis, black-grain mycetoma, and phaeohy phomycosis. While there are many kinds of dematiaceous fungi, the major etiologic agent is Fonsecaea pedrosoi, which to date has accounted for 90% of chromoblastomycosis cases. The genus Fonsecaea has recently been assessed via rRNA ITS sequence analysis, and species have been classified into F. pedrosoi, F. monophora, and others. We encountered two cases of chromomycosis that had developed on facial and upper arm areas. Neither of the etiologic agents could be identified through morphological examination under a microscope; however, F. monophora was confirmed using molecular phylogenetic analysis. Indeed, molecular phylogenetic analysis has revealed that the etiologic agents in many reported cases of F. pedrosoi infections were actually F. monophora. This suggests that it is now necessary to reconsider the classification of genus Fonsecaea.