Dermoscopic Features of Nail Psoriasis: An Observational, Analytical Study

Abstract

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.

A dermoscopic study of nail involvement in chronic plaque psoriasis at a tertiary care center

“…Pseudofiber sign is described as filamentous structures which are red and black in color, located in proximity to the cuticle or under the hyponychium and it is suggested to be the representative of bare capillaries related to nail bed psoriasis. 12 In our present dermoscopic study, we reported this finding in 16.1% (n=25) of our patients. The other dermoscopic study which reported pseudo-fiber sign is Wannaing et al, 9 in which 18% of their psoriatic patients had this feature on dermoscopic examination.…”

“…2 We reported this finding in 11.6% of our patients on dermoscopic examination. Polat and Kapicioglu, 4 and Chauhan et al, 12 also observed red spots in lunula in 5% and 10% of their patients, respectively.…”

“…In our present study, we noted the presence of dilated capillaries in the proximal nail fold on dermoscopic examination in 12.3% of patients. A study by Chauhan et al,12 also reported dilated nailfold capillaries in proximal nailfold in 5.8% and 0.9% of fingernails and toenails respectively. Zaric et al, 14 and Bushan et al, 15 both reported a reduction in the size of capillaries of proximal nailfold in psoriatic patients with psoriatic arthritis.…”

“…Fuzzy lunula is another newly reported feature of nail psoriasis first described by Chauhan et al,12 as irregular wide white lunula which was observed in 30.90% of their patients. We also noted this appearance of fuzzy lunula in 7% (n=11) of our patients.…”

“…Dilated capillaries observed in the hyponychium could be due to the underlying changes in the dermal vasculature and were observed in 7.7% (n=12) of patients in our dermoscopic study. Dermoscopy of hyponychium on clinically involved nails showed dilated tortuous and irregularly arranged capillaries in fingernails of 2.9% of patients and in toenails of 0.9% of patients in a study conducted by Chauhan et al, 12 Wanniang et al, 9 reported this finding in 10% of their cases.…”