[Differential diagnostic spectrum of psoriasis vs. psoriatic arthritis in skin and joints]

Psoriasis and psoriatic arthritis are common disease entities in the daily routine of dermatologists and rheumatologists. The clinical management of the diseases profits tremendously from interdisciplinary contacts and shared decision-making processes. For dermatologists, recognition of early clinical symptoms of inflammatory arthropathies is pivotal. Rheumatologists, on the other hand, are required to make an early assessment of skin and nail changes in patients, since they are important parameters in the clinical classification of inflammatory joint diseases, in particular for the diagnosis of psoriatic arthritis. In patients with psoriasis, lesions on the scalp, in the anal cleft, and nail changes as well as severe generalized skin disease are all regarded as risk factors for psoriatic arthritis. The symptoms of the associated joint and spinal afflictions can vary considerably and confirmation of the diagnosis, in particular in early stages of the disease often represents a considerable challenge. The most common clinical manifestations of psoriasis and psoriatic arthritis and their differential diagnostics are discussed.