History: This patient has had a dermatitis of the dorsum of his right hand for 8 - 10 months. He saw his PCP on a number of occasions and was treated with triamcinalone 0.1% cream and clobetasol 0.05% ointment (a super potent topical corticosteroid!). Some of the redness and scale improved, but process recurred when topicals were stopped. Good general health. Takes no meds by mouth.
O/E: Fairly well-demarcated dermatitis on dorsum of right hand. No scale. There are faint papules which may represent areas of increased fungal load.
Clinical Photo(s)
Lab: KOH pep loaded with septate hyaline hyphae.
Histopathology: N/A
Diagnosis or DDx: Tinea incognito
Questions: N/A
Reason(s) Presented: Topical steroids can change appearance of tinea. They suppress local inflammation and ablate the scaly surface. When they are stopped the process recurs. The corticosteroid facilitates fungal growth by suppressing local inhibitory factors. The tip off here was the localization on one hand and the relatively sharp border. There's a saying "Do a KOH prep when it is indicated and do one when it isn't indicated and you won't make many mistakes."
Reference:
Tinea incognito in Italy: a 15-year survey.
Mycoses. 2006 Sep;49(5):383-7.
Romano C, Maritati E, Gianni C
Institute of Dermatological Sciences, University of Siena, Via Monte Santo 3,
Tinea incognito or steroid modified tinea is a dermatophytic
infection in whichtopical or systemic steroids, administered
as a result of dermatological misdiagnosis or preexisting
pathologies, have modified the clinical appearance of the fungal
infection, transforming the typical ringworm and mimicking other
skin diseases. This is a retrospective study of the agents,
clinical aspects, sources of infection of 200 cases (98 males,
102 females, mean age 42 years) of tinea incognito, observed in
Siena and Milan, Italy, in the period 1987-2002. The clinical
appearance of the infection was lupus erythematosus discoid-like,
eczema-like, rosacea-like, especially on the face, impetigo-like
and eczema-like on trunk and limbs. Less often the dermatophytosis
resembled psoriasis, purpura, seborrhoic dermatitis and lichen
planus. There was folliculitis in 9% of cases and dermatophytid
in 3% of cases. Antimycotic therapy brought about clinical and
mycological recovery in allpatients except one, who had iatrogenic
immunodepression.
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