Intra-operative dermoscopy (onychoscopy) of the nail unit-A systematic review

Dermoscopy of the nail unit (onychoscopy) is a method which allows for non-invasive observation of the nail structures, increasing the accuracy of clinical diagnosis. Currently, it is used in evaluation of both inflammatory and neoplastic conditions of the nail unit. However, in contrast to the skin, the anatomy of the nail unit prevents direct observation of nail bed or nail matrix structure during classic onychoscopy. Intra-operative onychoscopy is a variant of the technique which uses direct visualization of the nail unit structures after nail plate avulsion. The aim of this systematic review was to summarize the current state of knowledge on intra-operative onychoscopy. The MEDLINE, EMBASE and Cochrane databases were systematically searched in January 2024. All types of study designs assessing intra-operative dermoscopy of the nail unit were included in this study. The risk of bias in included studies was assessed using the Joanna Briggs Institute critical appraisal tools. The qualitative synthesis of 19 studies totalling a number of 218 cases in 217 patients included the following entities: melanoma, nevus, hypermelanosis (melanocytic activation), melanocytic hyperplasia, melanophages accumulation, squamous cell carcinoma, glomus tumour, lichen planus, onychomatricoma, onychomycosis and subungual exostosis. The main limitation of the study was a relatively low number of identified studies, most with low levels of evidence. Intra-operative onychoscopy does not replace histologic examination, though it may be useful in determining the modality of surgical diagnostic procedures.