Introduction: Nail involvement in psoriasis occurs in up to 30-50% of patients, and 5-10% may have isolated nail disease. Onychoscopy, a noninvasive tool, might obviate the need for nail biopsy, which is a diagnostic gold standard.
Objective: The aim of this study was to evaluate onychoscopic features of nail unit in patients with nail psoriasis.
Methods: Fifty-five patients with clinically diagnosed and histologically documented nail psoriasis were recruited. Onychoscopy was performed for each nail (excluding the 5th toenail). Clinically, 443/550 fingernails and 101/440 toenails were involved. The frequency distributions of various onychoscopic features was assessed and compared using the χ2 test (p value <0.05 was considered significant).
Results: With onychoscopy, additional 52 fingernails and 64 toenails showed psoriatic involvement. Pitting was the commonest finding in fingernails (60.5%) followed by subungual hyperkeratosis (SUH) (52.8%), onycholysis (40.8%), and dotted capillaries in hyponychium, proximal, and lateral nail folds (38.6 vs. 35.8 vs. 35.8%). In toenails, we observed SUH (85.1%), nail plate thickening (82.1%), onycholysis (77.2%), and dotted capillaries in hyponychium and nail folds (59.4 vs. 53.4 vs. 45.5%). Fuzzy lunula was a novel onychoscopic finding noted in 33.6% fingernails and 4.95% toenails (p < 0.00001).
Limitations: Small sample size.
Conclusions: Onychoscopy may aid in diagnosing nail lesions even before the clinical signs are apparent.
Keywords: Dermoscopy; Fuzzy lunula; Nail pitting; Nail psoriasis; Oil spot/salmon patch; Red lunula.
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