Tinea incognita pathology
Tinea incognita (often spelled incognito) is an atypical presentation of tinea infection when topical steroid applications are used incorrectly for the treatment of dermatophytosis. The disease extends despite improvement of itch.
Histology of tinea incognita
In tinea incognita, the epidermis is often mildly spongiotic, and the dermal inflammatory infiltrate is less heavy than usual dermatophytosis. Multiple branched, septate hyphae and small spores are present in the stratum corneum. These can often be seen on H-E stain (figures 1, 2, 3) but special stains are often needed to reveal the fungi and demonstrate their morphology.
Images provided by Dr Duncan Lamont, Waikato Hospital
Special studies in tinea incognita
Fungal hyphae are positive on PAS stain and Gomori methenamine silver stain.