Comparison of Diagnostic Methods in the Evaluation of Onychomycosis Iman Haghani • Tahereh Shokohi • Zohreh Hajheidari • Alireza Khalilian • Seyed Reza Aghili Received: 24 August 2012 / Accepted: 21 January 2013 / Published online: 1 February 2013 Ó Springer Science+Business Media Dordrecht 2013 Abstract Onychomycosis is a common nail prob- lem, accounting for up to half of all nail diseases. Several nail disorders may mimic the onychomycosis clinically. Therefore, a sensitive, quick, and inexpen- sive test is essential for screening nail specimens for the administration of the proper drug. The aim of this study was to compare 4 different diagnostic methods in the evaluation of onychomycosis and to determine their sensitivity, specificity, positive predictive value, and negative predictive value. In a cross-sectional study, nail specimens were collected from 101 patients suspected to have onychomycosis during a 14-month period. The nail specimens were examined using potassium hydroxide (KOH) 20 %, KOH-treated nail clipping stained with periodic acid-Schiff (KONCPA), and calcofluor white (CFW) stain, and grew a fungal culture. The culture was chosen as the gold standard for statistical analysis using the McNemar and chi-square tests. Out of 101 patients, 100 (99 %) patients had at least 1 of the 4 diagnostic methods positive for the presence of organisms. The positive rates for the fungal culture, KOH preparation, CFW, and KONCPA were 74.2, 85.1, 91.09, and 99.01 %, respectively. The sensitivity and negative predictive value of KONCPA was 100 %. KONCPA was the most sensitive among the tests and was also superior to other methods in its negative predictive value. KONCPA was easy to perform, rapid, and gave significantly higher rates of detection of onychomycosis compared to the standard methods of KOH preparation and fungal culture. Therefore, KONCPA should be the single method of choice for the evaluation of onychomycosis. Keywords Calcofluor white (CFW) staining Á Culture Á Diagnosis Á KOH preparation Á KOH-treated nail clipping stained with PAS (KONCPA) Á Onychomycosis Introduction Onychomycosis is a common disorder of the nail plate caused by fungal elements and represents approxi- mately 50 % of nails’ disorders and 30 % of all superficial mycotic infections [1]. Onychomycosis is not a life-threatening infection, but can seriously I. Haghani Á T. Shokohi (&) Á S. R. Aghili Department of Medical Mycology and Parasitology, Sari Medical School, Invasive Fungi Research Center, Mazandaran University of Medical Sciences, 18 km Khazar Abad Road, P.O Box 48175-1665, Sari, Iran e-mail: shokohi.tahereh@gmail.com Z. Hajheidari Department of Dermatology, Sari Medical School, Mazandaran University of Medical Sciences, Sari, Iran A. Khalilian Department of Community Medicine, Sari Medical School, Mazandaran University of Medical Sciences, Sari, Iran 123 Mycopathologia (2013) 175:315–321 DOI 10.1007/s11046-013-9620-9