Linear Pitting and Splinter Haemorrhages Are More Commonly Seen in the Nails of Patients with Established Psoriasis in Comparison to Psoriatic Arthritis

Background: Recently the role of several ligament and tendon insertions around the nail matrix and nail plate have been identified as possible contributory factors that explain the higher prevalence of nail involvement in psoriatic arthritis (PsA). The purpose of this study was to determine whether such anatomical factors might also be associated with different patterns of nail involvement in skin psoriasis and PsA.

Methods: A total of 173 patients were recruited: 121 PsA cases and 52 psoriasis cases. All patients had a standardised assessment of the nails for lesions including pitting, splinter haemorrhages and onycholysis.

Results: The overall modified Nail Psoriasis Severity Index scores did not differ between the two groups (psoriasis mean 8.5, SD 7.1; PsA mean 8.3, SD 9.4). In the nail matrix, linear pitting appeared to be more common in skin psoriasis (OR 0.27, 95% CI 0.18-0.41). There were no significant differences in the distribution of nail plate abnormalities other than splinter haemorrhages which were more commonly seen in psoriasis cases (OR 0.23, 95% CI 0.14-0.39).

Conclusion: The pattern of nail disease in psoriasis and PsA differed with respect to the frequency of linear pitting and splinter haemorrhages, with both features occurring more often in psoriasis.