The onychomycosis/onychodystrophy dermoscopy study
Rita Ramos Pinheiro1, Tiago Dias Domingues2, Virgínia Coelho de Sousa1, Célia Galhardas1, Margarida Apetato1, André Lencastre1
1-Dermatology Department, Hospital Santo António dos Capuchos, Centro Hospitalar Lisboa Central, Lisbon, Portugal; 2- CEAUL - Centro de Estatística e Aplicações da Universidade de Lisboa
Onychomycosis (OM) and traumatic onychodystrophy (OD) are common toenail abnormalities. Their treatment and prognosis differ, so early diagnosis is essential and questionable without mycology. The latter includes both direct microscopy and cultural examination which are time-consuming procedures with low sensitivity and specificity.1,2 Invasive procedures such as punch biopsy or nail clipping for histological examination are occasionally needed to establish the diagnosis.1
Dermoscopy is widely used for the diagnosis of neoplastic, melanocytic and inflammatory skin diseases; although its application for nail disorders namely OM is currently poorly recognized.
Three studies3,4,5 have addressed this issue and their findings are concordant. Two major onychoscopic features associated with OM have been described:3,4,5 longitudinal striae and an irregular “jagged edge” of the affected area with spikes.
We aimed to identify and describe onychoscopic patterns associated with OM and OD, proposing an onychoscopy-based algorithm to guide their differential.
We performed an observational prospective study that included all outpatient consecutive clinical attendees presenting with changes of at least one toenail.
Exclusion criteria: systemic antifungal use in the last year or topical OM therapy the month before inclusion; psoriasis, lichen planus or other inflammatory onycopathy diagnosis.
All patients underwent physical, onychoscopic, nail clipping and mycological examinations. Only the most relevant/representative pattern of nail changes on onychoscopy was analyzed. We evaluated onychoscopy, comparing it with clinical and mycological findings, looking for an association between onychoscopic patterns and OM or OD. All results with a p-value less than 0.05 were considered statistically significant. The software used was SPSS version 23.
131 patient were evaluated for toenail onychodystrophy in the study period: 11 were excluded due to recent topical or oral antifungal therapy; 7 due to an inflammatory nail disease diagnosis. 113 patients were included. Demographic data, onychoschopic patterns and mycological results are analysed in Panel A. Onychoscopic patterns are illustrated in Panel B.
Our results are concordant with previous studies. The irregular macular pattern with spikes, the longitudinal lines and the distal pulverization patterns were significantly associated with OM (p<0,05). Additionally, we found a statistically significant association between 3 patterns and an OD diagnosis – the total and partial hazy homogeneous background, and the fine lines pattern (p<0,05).
Our results showed distinctive onychoscopic findings of OM and OD. Detection of these patterns is simple and can rapidly guide the diagnosis before mycology results are available.