Clinical Diagnostic Accuracy of Onychomycosis: A Multispecialty Comparison Study

Abstract

Although onychomycosis can be diagnosed clinically, many guidelines still recommend pathologic confirmation of the diagnosis prior to initiation of systemic treatment. We retrospectively reviewed results from 541 toenail clippings (160 by dermatologists, 198 by podiatrists, and 183 by other provider types) sent to the Brigham and Women's Department of Dermatopathology between January 2000 and December 2013 for confirmatory periodic acid-Schiff (PAS) testing of clinically diagnosed onychomycosis. Of these, 93 (58.1%), 125 (63.1%), and 71 (38.8%) were sent for confirmation of onychomycosis (as opposed to diagnosis of onychodystrophy) by dermatologists, podiatrists, and other provider types, respectively. Confirmatory PAS stains were positive in 70 (75.3%), 101 (80.8%), and 47 (66.2%) of samples ordered by dermatologists, podiatrists, and other providers, respectively. Our study demonstrates that clinical diagnosis of onychomycosis in the appropriate clinical setting is accurate across specialties. Further prospective investigation on the accuracy of clinical diagnosis of onychomycosis may be beneficial.

Onychomycosis: An Updated Review

“…A diagnosis of onychomycosis can be strongly suspected based on the typical clinical features such as nail discoloration, subungual hyperkeratosis/debris, onycholysis, and onychauxis [ 46 , 66 , 67 ]. In one study, the clinical diagnostic accuracy of onychomycosis among non-dermatologists and dermatologists was approximately 66% and 75%, respectively [ 68 ]. Dermoscopy of the nails is a useful, quick, non-invasive, and highly effective tool that may help to differentiate onychomycosis from other nail disorders [ 36 , 69 ].…”

“…A potassium hydroxide preparation is a useful screening test to rule out the presence of fungi which provides almost immediate results at low cost [ 36 , 68 , 80 ]. The test is performed by adding a drop of 10 to 20% potassium hydroxide, to the nail specimen which is placed on a glass slide for examination by light microscopy [ 64 , 78 ].…”

“…However, the species of the offending fungus and its viability cannot be determined in a PAS stain [ 32 , 36 , 78 ]. The cost associated with PAS stain is higher than potassium hydroxide preparation [ 36 , 68 , 78 ]. PAS stain is also more labor intensive than potassium hydroxide preparation [ 6 ].…”

The Canadian Dermatology Association’s Top Five Choosing Wisely Canada Recommendations

“…Although clinical diagnostic accuracy has been found to vary between healthcare providers, 24 all physicians should obtain mycological confirmation of onychomycosis before proceeding to therapy with antifungal treatment. Diagnosis can be easily achieved by simple potassium hydroxide (KOH) microscopy, fungal culture, or histopathology.…”

Profile of The Incidence of Onychomycosis at RSUD Dr RM Djoelham Binjai for Period January 2017 – December 2021

“…It often occurs in adults and affects 8% of patients who come for treatment. (Li et al, 2018). The disease is increasing in both adults and children.…”