Nail dermoscopy (onychoscopy) findings in the diagnosis of primary onychomycosis: A cross-sectional study.

Background: Diagnosis of onychomycosis involves direct microscopic examination with potassium hydroxide, culture or histopathology with periodic acid-Schiff staining. Nail dermoscopy (onychoscopy) is a noninvasive, rapid and easily available diagnostic tool though its utility in onychomycosis remains unexplored.
Objective: To describe the various onychoscopic patterns and compare its percentage positivity with that of standard potassium hydroxide examination, culture and histopathology in patients with a clinical diagnosis of onychomycosis.
Methods: The study recruited 100 patients with a presumptive clinical diagnosis of onychomycosis. A detailed history, physical examination including that of nails and clinical photography was followed by onychoscopy with DermLite DL3. The nail clippings were sent for direct microscopic examination with potassium hydroxide, mycological culture and histopathology with periodic acid-Schiff stain. The patient was said to have onychomycosis if at least one of the three tests was positive.
Results: Onychomycosis was confirmed by potassium hydroxide and/or culture and/or histopathology in 88 patients. Onychoscopic features were identified and their association with different clinical variants of onychomycosis was attempted. Percentage positivity for diagnosing onychomycosis in decreasing order was: direct microscopic examination with potassium hydroxide followed by spiked pattern, subungual hyperkeratosis, distal irregular termination on onychoscopy, histopathology, mycological culture and ruins aspect again observed on onychoscopy.
Limitations: Small sample size.
Conclusions: Many onychoscopic features are highly specific for different variants of onychomycosis so onychoscopy may serve as an important and quick adjunct to diagnose onychomycosis until other time-consuming investigations, such as culture and periodic acid-Schiff become available. Studies on a larger population will help arrive at a logistic conclusion.
Competing Interests: None