The diagnostic and therapeutic challenge of early psoriatic arthritis.

Psoriasis is a complex disease involving the skin, nails and musculoskeletal structures. Psoriatic arthritis (PsA) affects peripheral joints, entheses, the synovial sheaths of tendons and the axial skeleton. PsA is now recognised as a potentially debilitating disease, with bone erosions and deformities affecting about half of patients and arising early after disease onset. Because PsA usually coincides with or follows the development of psoriasis, dermatologists are in a strategic position to diagnose and manage early PsA. In general, patients with severe psoriasis appear to have a higher risk of arthritis than patients with mild psoriasis. In addition, scalp lesions, nail dystrophy and intergluteal/perianal lesions have been found to be associated with a higher risk of PsA development. The diagnosis of PsA is based primarily on clinical features, and several classification criteria have been developed. Ultrasonography, magnetic resonance imaging and bone scintigraphy, rather than standard radiography, are the most accurate and effective diagnostic imaging approaches for documenting early PsA. The therapeutic strategy for early PsA should be aimed at inducing lasting remission, preventing permanent damage and possibly modifying the natural disease course.