An experience of tinea incognito

Tinea incognito was first described more than fifty years ago and occurs worldwide. It is a fungal infection of the skin, commonly caused by dermatophyte trichophyton (less frequently by microsporum. The typical features of the fungal skin eruption are masked due to altered/impaired local immunity by the use of topical steroids or calcineurin inhibitors. Other predisposing causes are diabetes, systemic immunosuppressants and HIV/AIDS.

The classical appearance of the annular lesion with central clearing and active scaly spreading boarder (‘ring worm’) which occur in fungal skin infection is replaced by various morphological features mimicking various dermatoses. Hence it can be easily misdiagnosed as psoriasis, eczema or folliculitis. The clues to the diagnosis are certain body sites, (face, ankle, groin or a limb) unilateral distribution, (occasionally widespread) and the history of application of topical steroid or other immunomodulators.