Nail psoriasis as a predictor of the development of psoriatic arthritis.

Psoriatic arthritis is a psoriasis-related spondyloarthropathy that occurs in 20-30% of patients with psoriasis. Various imaging studies have demonstrated that there is a considerable proportion of undiagnosed psoriatic arthritis among patients with psoriasis. Since early detection and treatment of psoriatic arthritis could, ultimately, allow the prevention of clinical and radiologic progression of the disease, there is the need to establish clinical indicators to detect this risk. Nail psoriasis has been proposed as a predictor for the development of psoriatic arthritis. The inflammation involving the entheses, called enthesitis, is an early inflammatory change seen in psoriatic arthritis, and nail changes appear to result from the close relationship between the nail and the enthesis of the distal interphalangeal extensor tendon, one of the main entheseal compartments affected in psoriatic arthritis. As skin lesions precede articular symptoms in more than 75-80% of patients with psoriatic arthritis, dermatologists may play a key role in the early detection and management of psoriatic arthritis.