[Crystal arthropathies].

Crystals are one of the commonest reasons for acute joint inflammation. The most relevant types of crystals are those of monosodium urate (MSU) and calcium pyrophosphates (CPP). To get proven diagnosis of a crystal arthropathy the microscopic identification of those crystals in synovial fluid is still recommended by the actual guidelines. Whenever arthrocentesis is not feasible, ultrasound or dual-energy-computed tomography might help to visualize specific changes induced especially by MSU crystals. Both types of crystals act as danger signals inducing flares of immediate inflammatory response via activation of the innate immune system. Therefore crystal arthropathies could be seen as an auto-inflammatory condition. As neutrophils, monocytes and macrophages are the key cells and Interleukin 1β is one of the dominant cytokines the way of blocking inflammation by colchicine and override IL-1β are specific options in treating inflammation due to the crystals. For gout, causal treatment with urate lowering therapy can result in clearance of urate crystals. Unfortunately, to date there is no causal therapy for CPPD available. The present article summarises the recent knowledge highlighting the news regarding the crystal arthropathies gout and CPPD.