Author: Hon A/Prof Amanda Oakley, Dermatologist, Hamilton, New Zealand. 2003. Updated by Dr Jannet Gomez, November 2017.
Tinea incognita is the name given to a fungal skin infection when the clinical appearance has been altered by inappropriate treatment, usually a topical steroid cream. The result is that the original infection slowly extends.
Often the patient and/or their doctor believe they have a dermatitis, hence the use of a topical steroid cream. The steroid cream dampens down inflammation so the condition feels less irritable. But when the cream is stopped for a few days the itch gets worse, so the steroid cream is promptly used again. The more steroid applied, the more extensive the fungal infection becomes and the less recognisable.
Tinea incognita is often incorrectly spelled as tinea incognita. It is also known as steroid-modified tinea.
Tinea incognita is due to dermatophyte fungal infection (tinea), most often when it affecting the trunk and/or limbs (tinea corporis). Trichophyton rubrum is the most common organism to cause tinea corporis and tinea incognita in New Zealand.
Anti-inflammatory creams that can induce tinea incognita include:
Tinea incognita can also be caused by systemic steroids.
Underlying diseases may predispose individuals to infection, especially:
Factors such as sweating, abrasion, and maceration also contribute to the development of infection.
There may also be secondary changes caused by long term use of a topical steroid such as:
The diagnosis of tinea is most easily made by taking skin scrapings for microscopy and culture a few days after stopping all creams.
Tinea is usually treated with topical antifungals (such as miconazole, ketoconazole, econazole), but if the treatment is unsuccessful, oral antifungal medicines may be considered, including terbinafine and itraconazole.
Tinea incognita can be avoided if:
Sahoo AK, Mahajan R. Management of tinea corporis, tinea cruris, and tinea pedis: A comprehensive review. Indian Dermatol Online J. 2016 Mar-Apr;7(2):77-86. doi: 10.4103/2229-5178.178099. Review. PubMed PMID: 27057486; PubMed Central PMCID: PMC4804599.
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