Epidemiology.-Introduction.-Psoriatic plaques in patients with PsA.-Incidence and prevalence.-Patterns of onset.-Quality of life.-Natural history.-Genetics.-Etiology and Pathophysiology.-Introduction.-Mechanisms of joint destruction.-Clinical Evaluation.-Introduction.-Moll and Wright classification.-DIP joint involvement.-Assymetric oligoarthritis.-Symmetric polyarthritis.-Axial involvement.-Arthritis mutilans.-Physical symptoms and signs.-Case history 1.- Case history 2.-Other diagnostic criteria sets.-Differential diagnosis of PsA.-Imaging.-Plain radiography.-Ultrasonography.-Magnetic resonance imaging.-Computerised tomography.-Skin and Psoriasis.-Introduction.-The psoriasis phenotype.-The Management of Psoriatic Arthritis.-Introduction.-Assessment of joint response in PsA.-Disease-modifying anti-rheumatic drugs (DMARDs).-Pathogenesis of PsA and opportunities for targeted treatment.-Biologic Agents.-New therapies.-Treatment of Psoriasis.-Introduction.-Assessment of response to psoriasis therapy.-Topical agents.-Phototherapy.-Systemic therapy for psoriasis.-Biologic agents for psoriasis.-