Histopathologic evidence of the nondermatophytic mould Scopulariopsis brevicaulis masking the presence of dermatophytes in a toenail infection.

Nondermatophytic toenail infection with Scopulariopsis brevicaulis is rare, but may occur often in association with dermatophytes. We report a case of an 84-year-old man who presented with onychomycosis of the big toenail. Histopathologic examination of the avulsed nail showed evidence of S. brevicaulis coinfection with a dermatophyte, despite negative mycology results for the latter. Our case underscores the importance of histopathologic examination of nail specimens as an additional invaluable tool in the diagnosis of onychomycosis, as it may unmask false-negative mycology findings.