The Use of Adhesive Tapes to Transfer Skin-scrapings for Sequential Laboratory Diagnosis of Dermatophytosis.

BACKGROUND: Dermatophytosis usually causes a skin problem, which requires both clinical findings and laboratory investigations for diagnosis. Whereas, fungal culture is considered as the gold standard procedure, it is more difficult to perform compared to potassium hydroxide（KOH）examination. OBJECTIVE: To evaluate the efficacy of KOH and fungal culture examinations from skin-scraping specimens, which were kept in transparent adhesive tapes at different time intervals. METHODS: Skin-scraping specimens were collected from clinically suspected cases by conventional technique using scalpel blades and kept using transparent adhesive tapes. KOH（10%）preparation and fungal cultures were then performed by highly experienced technicians at different time intervals: day 0（the day of specimen collection, which was set as the standard reference point）, day 3 or 4, day 7, day 14, and day 28. Thereafter, the yield for detection of fungal elements by KOH examination and positive fungal cultures from specimens stored in adhesive tape was determined at different time intervals and compared to the results from the standard reference point. RESULTS: The sensitivity of KOH exami-nations from 162 patients at different time intervals showed no significant difference when compared to the standard reference point at day 0. In contrast, the sensitivity of fungal culture progressively decreased as the storage period was prolonged. CONCLUSIONS: KOH examination of skin-scrapings from the adhesive tape storage technique yield good results even when specimens have been kept up to one month. On the other hand, the sensitivity of fungal cultures gradually declines as storage time is extended.

Tinea capitis caused by Trichophyton tonsurans presenting as an obscure patchy hair loss due to daily antifungal shampoo use.

Tinea capitis is unusual and often misdiagnosed in healthy adults. We report a case of a healthy woman with a several-year history of asymptomatic, bizarre-shaped, non-scarring alopecia. She had used over-the-counter ketoconazole shampoo regularly for a long time. An initial potassium hydroxide preparation showed negative result for fungal organism. The scalp biopsy revealed endothrix infection, and dermoscopic examination demonstrated the comma hair and corkscrew hair signs. The fungal culture showed Trichophyton tonsurans. The daily use of antifungal shampoo could be the important factor to conceal clinical and laboratory findings for diagnosis of T. tonsurans tinea capitis in our case, which required high clinical suspicion and histopathology and dermoscopic examinations.