KONCPA: a new method for diagnosing tinea unguium.

Tinea unguium (TU) is very common in tropical and subtropical regions. An inexpensive, quick and sensitive test is essential for screening the nail specimens. We investigated if a test using potassium hydroxide (KOH)-treated nail clippings, which were then crushed and stained with periodic acid-Schiff (PAS), could be useful for diagnosing TU. The new method (abbreviated as KONCPA) was proved to be more fruitful to identify fungal hyphae in comparison with conventional KOH nail scraping preparation, histopathologic examination and fungal culture. The positive rates of each method were 77, 44, 60 and 16%, respectively. All 10 KONCPA-negative nails failed to show fungus by the other three methods. The KONCPA slides can be permanently stored as records. In addition, we also found that treatment of nail specimens in 20% KOH at 56 degrees C for 10 min prior to histopathologic processing is a simple method to soften the nail plate.