The role of dermoscopy in the diagnosis of nail affection of psoriasis and lichen planus

Background Nail disorders comprise ∼10% of all dermatological conditions. Because diagnosis is not always possible by clinical means alone, additional diagnostic procedures may be required at times. Dermoscopy of nails (onychoscopy) has shown promising results in diagnosing various nail disorders. Aim To study the dermoscopic nail findings in psoriasis and lichen planus. Patients and methods A total of 80 patients with clinically evident psoriasis and lichen planus of nail were included in this study. They were classified into two groups: group 1 included 40 patients with nail psoriasis and group 2 included 40 patients with nail lichen planus. All patients were examined clinically and by dermoscope for criteria of psoriasis and lichen planus of the nails. Results In psoriatic patients, pitting is the commonest finding observed clinically and by dermoscope. Splinter hemorrhage, pitting, leukonychia, longitudinal ridging, oil drop sign, and onycholysis are better visualized by dermoscopy, and dilated hyponychial capillaries are detected only by dermoscopy. In patients of lichen planus, longitudinal ridging is the commonest finding observed clinically and by dermoscopy. Longitudinal ridging, pitting, chromonychia, and splinter hemorrhage are better seen by dermoscopy. Linear dyschromic bands are not detected clinically. Conclusion Onychoscopy can provide valuable diagnostic information in cases of nail psoriasis and nail lichen planus.