Ultrasound entheseal abnormalities at the distal interphalangeal joints and clinical nail involvement in patients with psoriasis and psoriatic arthritis, supporting the nail-enthesitis theory

Nail disease was associated with DIP US enthesopathy. There was a significant increased prevalence of extensor tendon enthesopathy in fingers with involved nails both in PsO and PsA, although no association was found between nail involvement and extensor tendon enthesopathy at patients' level. These features might support the nail-entheseal pathogenesis theory at DIP level.