Detection of subclinical ultrasound enthesopathy and nail disease in patients at risk of psoriatic arthritis.

Objectives: To detect subclinical entheses and nail abnormalities using gray-scale (GS) and power Doppler ultrasonography (PDUS) between patients with nail psoriasis and those with inverse and scalp psoriasis.

Methods: In this prospective monocentric study, patients with nail, inverse and scalp psoriasis, without psoriatic arthritis or systemic treatment, were included. Clinical evaluation and ultrasonographic assessment of 14 entheses and 12 nails were done by a dermatologist (clinical assessment) and a rheumatologist (ultrasonographic assessment).

Results: 518 entheses were analyzed, with no statistical difference between the two groups when considering GS enthesopathy (P=0.66). PDUS signal of the entheses were low (<1%) in both groups. Matrix thickness was significantly higher in patients with nail disease (1.94mm vs. 1.77mm; P=0.007). PDUS of the skin thickness at the level of distal joint and the loss of the trilaminar appearance were also significantly associated with nail psoriasis (P=0.037 and P<0.0001 respectively).

Conclusion: Detection of subclinical US enthesopathy is not so rare in both groups, unlike PD signal, but with no statistical difference. US are a good tool to evaluate the different components of psoriatic nails (loss of trilaminar appearance, nail thickening and inflammation of the skin thickness) which are significantly associated with nail psoriasis.