Cryofibrinogenemia: What Rheumatologists Should Know.

Cryofibrinogenemia refers to the presence of cryofibrinogen in plasma. This protein has the property of precipitating at lower temperatures. Cryofibrinogenemia is a rare disorder, clinically characterized by skin lesions, such as ulcers, necrosis, livedo reticularis, arthralgia, thrombosis, and limb ischemia. These features are most often observed in rheumatological practice and consist of differential diagnoses of antiphospholipid syndrome, primary vasculitis, thrombotic thrombocytopenic purpura, and cryoglobulinemia. Classical histopathological findings include the presence of thrombi within the lumen of blood vessels of the skin without vasculitis. To date, there are no validated classification criteria. Management includes corticosteroids, immunosuppressive therapy, anticoagulants, and fibrinolytic agents. This narrative review aims to make physicians, particularly rheumatologists, aware of the existence of this underdiagnosed condition. There are no epidemiological studies evaluating the prevalence of cryofibrinogenemia in different rheumatological disorders. Studies are also required to investigate if certain features of rheumatological diseases are related to the presence of cryofibrinogenemia.