A widespread annular eruption became less scaly and more extensive after potent topical corticosteroid. Tinea incognito is suspected. Which sampling

Question

A widespread annular eruption became less scaly and more extensive after potent topical corticosteroid. Tinea incognito is suspected. Which sampling technique offers the best chance of confirming dermatophyte infection?

Accepted Answer

Stop corticosteroid and scrape active peripheral scale for microscopy and fungal culture

Answer

Take a surface swab after applying antifungal cream and request anaerobic bacterial culture

Answer

Biopsy uninvolved skin for direct immunofluorescence and send no sample for mycology

Answer

Swab the clinically normal centre for routine bacterial culture while continuing the corticosteroid

Answer

Pluck normal hairs outside the eruption and request viral polymerase-chain-reaction testing

Tinea Incognito — SCE Dermatology MCQ

A widespread annular eruption became less scaly and more extensive after potent topical corticosteroid. Tinea incognito is suspected. Which sampling technique offers the best chance of confirming dermatophyte infection?