Authors: Dr Achala Liyanage, Dermatology Fellow, Waikato Hospital, Hamilton, New Zealand; Assoc Prof Patrick Emanuel, Dermatopathologist, Auckland, New Zealand. January 2015.
Tinea incognito is an atypical presentation of tineainfection when topical steroid applications are used incorrectly for the treatment of dermatophytosis. The disease extends despite improvement of itch.
Histology of tinea incognito
In tinea incognito, the epidermis is often mildly spongiotic, and the dermalinflammatoryinfiltrate is less heavy than usual dermatophytosis. Multiple branched, septatehyphae 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.
Figure 1
Figure 2
Figure 3
Figure 4
Images provided by Dr Duncan Lamont, Waikato Hospital
Special studies in tinea incognito
Fungal hyphae are positive on PAS stain and Gomori methenamine silver stain.
References
Weedon’s Skin Pathology (Third edition, 2010). David Weedon
