​Schnitzler Syndrome

The first clinical sign is usually a mildly or non-pruritic (non-itchy) skin rash. Elementary lesions are rose or red macules (area of skin discolouration) or slightly elevated plaques, which resolve within 24 hours. Lesions can occur on any body part, though involvement of the face and extremities is rare. The frequency and duration of flares are variable. Almost all patients develop intermittent fever and body temperature can rise above 40 °C (104 °F). Fever is usually well tolerated and chills are rare. About 80% of patients experience bone and/or joint pain. Bone involvement is common, and 30 to 40% of patients show bone lesions on imaging studies. IgM (immunoglobulin M) levels can remain stable or progressively increase at a rate of about 0.5 to 1 g/L/year. Other signs include elevated erythrocyte sedimentation rate (ESR), inflammatory anaemia sometimes with thrombocytosis (up to 50% of cases), palpable lymph nodes (45%), and hepatic or splenic enlargement (30%). The monoclonal IgM component is a defining feature of the disease. Inflammatory AA amyloidosis may be a serious complication. The disease follows a chronic course.

The exact underlying cause of the condition is unknown; however, most cases occur sporadically in people with no family history of the condition. Treatment is focused on alleviating the signs and symptoms associated with the condition and may include various medications such as NSAIDs, corticosteroids, immunosuppressive agents, interleukin-1 receptor antagonists, colchicine, Dapsone, Thalidomide, Rituximab, and/or phototherapy.