Onychoscopy: A practical guide.

Onychoscopy refers to the examination of the nail unit using a dermoscope. Since the advent of dermoscopy, attempts have been made to use it for the diagnosis of nail disorders, most commonly pigmented lesions. As of now, onychoscopy has carved out a distinct niche for itself in the diagnostic work up of nail disorders. The nail is capable of mounting only a limited number of reaction patterns to the large number of disorders affecting it. Therefore, simple visual inspection may not be helpful in diagnosing many conditions reliably. Even a nail biopsy may not give a definitive answer every time. Onychoscopy is thus a valuable aid not only in enhancing visible nail features but also in revealing cryptic features of diagnostic value. This review aims to summarize the current level of knowledge about onychoscopic features of various diseases of the nail unit. It also aims to offer practical tips on how to conduct onychoscopy. For the purpose of review, a PubMed search about the indications and results of onychoscopy was done using the keywords "onychoscopy," "nail fold capillaroscopy," "dermoscopy nail" and "dermatoscopy nail." All the articles were retrieved and classified into case reports, reviews and clinical studies. The final data was then analyzed and presented in a narrative fashion.