Understanding Onychomycosis Resolving Diagnostic Dilemmas.

No scientifically rigorous, large, prospective studies have been done to document the true prevalence of onychomycosis; the reported rates vary mainly by climate and by population, but the overall prevalence in the United States is estimated to be at least 10%. Advanced age and diabetes are the most commonly reported risk factors for onychomycosis. The differential diagnosis of onychomycosis is lengthy, and visual inspection alone is not sufficient for a definitive diagnosis-direct microscopic examination of a wet-mount preparation with 10% to 20% potassium hydroxide is the first-line diagnostic test.