AB0796 PSORIATIC ONYCHOPATHY: MORE THAN MEETS THE EYE

Background: Psoriatic onychopathy is an independent predictor of the onset of psoriatic arthritis (PsA). Assessment of nail disease is difficult given the limited utility of clinical assessment tools for the nail. Recently, ultrasound (US) proved to be informative in the assessment of nail involvement. Objectives: We aimed to describe morphologic ultrasonographic nail disease changes and to look for correlations between these features and the characteristics of the PsA. Methods: The study included patients who met the CASPAR criteria for PsA. An US scan of patient’s nails was performed in order to study the nail, matrix and skin thickness. Results: We included 33 patients with PsA with a mean age of 51.2±12.5 years. The mean DAPSA was 22.8±19.7 (remission:9 patients, low activity: 5 patients, moderate activity: 11 patients and high activity: 8 patients). Twenty-nine patients had a personal history of skin psoriasis, present in 64 % of the patients the day of the examination with a mean PASI of 2.76 ±3.9. Eleven patients (33.4%) presented with psoriatic onychopathy (45 fingernails) with a mean mNAPSI of 14.1± 16. The most common patterns of nail involvement were: Oil-drop patches (5 fingernails), pitting (4 fingernails), onycholysis (3 fingernails), crumbling (3 fingernails), subungual hyperkeratosis (2 fingernails), leukonychia (2 fingernails), paronychia (2 fingernails), splinter hemorrhages (1 fingernail). We scanned 330 fingernails. The US study revealed dystrophy in 75 nails (22.7%) of the nails, in 17 patients (51.5%): Undulations or pitting (n=47), followed by disappearance of the anechoic space (n=38) and anechoic ventral nail plate (n=18). The mean thickness of skin, nail plate and nail matrix region were 2.25±0.32 mm, 0.38±0.07 mm and 1.89±0.33, respectively. We found a positive correlation between nail plate thickness and both skin and nail matrix region thickness (r=0.561, p=0.001 and r=0.523, p=0.002). Skin, nail and nail matrix thickness were significantly higher in men and in smokers. Manual workers did not have greater skin, nail plate nor nail matrix thickness. There were no correlations between disease activity evaluated by the ASDAS-CRP, DAS28, PASI, ESR or by CRP and any of the US parameters. In contrast, there was a significant negative correlation between psoriatic disease duration and nail plate thickness (r=-0.372, p=0,036). Conclusion: Ultrasound offers an appropriate alternative for the evaluation of the nail unit. In our study it was able to detect subclinical involvement of the nail in 30 fingernails and in two patients. Disclosure of Interests: None declared