{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,29]],"date-time":"2026-09-29T21:51:24Z","timestamp":1790718684442,"version":"4.1.0"},"reference-count":41,"publisher":"MDPI AG","issue":"2","license":[{"start":{"date-parts":[[2024,2,13]],"date-time":"2024-02-13T00:00:00Z","timestamp":1707782400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["JoF"],"abstract":"<jats:p>Onychomycosis is an under-recognized healthcare burden. Despite the risk of misdiagnosis, confirmatory laboratory testing is under-utilized. Histopathologic examination with polymerase chain reaction (PCR) is currently the most effective diagnostic method; it offers direct detection and identification of a fungal invasion. In this retrospective cohort study, we assessed confirmatory testing results, with matching clinical diagnoses, in 96,293 nail specimens submitted during a 9-month period from 2022 to 2023. Toenail specimens were examined using fungal culture, histopathology and\/or PCR. Clinical diagnoses were identified using the International Classification of Diseases 10th Revision codes. For clinically diagnosed onychomycosis patients, the overall positivity rate was 59.4%; a similar positivity rate (59.5%) was found in patients with clinically diagnosed non-fungal nail dystrophy. Performing a histopathologic examination with PCR was more likely to provide pathogen identification results than using fungal culture. Male patients had a higher rate of onychomycosis overall; however, female patients had more non-dermatophyte mold onychomycosis caused by Aspergillus. Clinically diagnosed onychomycosis patients with a co-diagnosis of tinea pedis were more likely to test positive for onychomycosis by PCR (odds ratio [OR]: 4.2; 95% confidence interval [CI]: 2.7\u20136.4), histopathology (OR: 2.5; 95% CI: 2.0\u20133.1) and fungal culture (OR: 3.2; 95% CI: 1.5\u20136.6). Our results support the use of confirmatory laboratory testing when there is a clinical diagnosis of onychomycosis.<\/jats:p>","DOI":"10.3390\/jof10020149","type":"journal-article","created":{"date-parts":[[2024,2,13]],"date-time":"2024-02-13T04:09:21Z","timestamp":1707797361000},"page":"149","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":21,"title":["Clinical Diagnosis and Laboratory Testing of Abnormal Appearing Toenails: A Retrospective Assessment of Confirmatory Testing for Onychomycosis in the United States, 2022\u20132023"],"prefix":"10.3390","volume":"10","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-8664-7723","authenticated-orcid":false,"given":"Aditya K.","family":"Gupta","sequence":"first","affiliation":[{"name":"Division of Dermatology, Department of Medicine, University of Toronto, Toronto, ON M5S 3H2, Canada"},{"name":"Mediprobe Research Inc., London, ON N5X 2P1, Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Tong","family":"Wang","sequence":"additional","affiliation":[{"name":"Mediprobe Research Inc., London, ON N5X 2P1, Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Elizabeth A.","family":"Cooper","sequence":"additional","affiliation":[{"name":"Mediprobe Research Inc., London, ON N5X 2P1, Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Sara A.","family":"Lincoln","sequence":"additional","affiliation":[{"name":"Bako Diagnostics, Alpharetta, GA 30005, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9640-9780","authenticated-orcid":false,"given":"Hui-Chen","family":"Foreman","sequence":"additional","affiliation":[{"name":"Bako Diagnostics, Alpharetta, GA 30005, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"William P.","family":"Scherer","sequence":"additional","affiliation":[{"name":"Bako Diagnostics, Alpharetta, GA 30005, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Wayne L.","family":"Bakotic","sequence":"additional","affiliation":[{"name":"Bako Diagnostics, Alpharetta, GA 30005, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2024,2,13]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"5","DOI":"10.1046\/j.1365-2133.149.s65.5.x","article-title":"Onychomycosis in Clinical Practice: Factors Contributing to Recurrence","volume":"149","author":"Scher","year":"2003","journal-title":"Br. 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