A rare complication in Schnitzler syndrome: recall urticaria in a patient treated with anakinra—a case report

Schnitzler syndrome is a rare acquired autoinflammatory disorder defined by a chronic urticarial rash, monoclonal IgM (or IgG) gammopathy, and systemic features including fever, arthralgia, and elevated inflammatory markers. Interleukin-1 blockade with anakinra is the current treatment of choice. We report the case of a 75-year-old woman who, after seven years of misdiagnosis as chronic spontaneous urticaria, fulfilled the Strasbourg Criteria for Schnitzler syndrome. Treatment with anakinra induced rapid clinical improvement but was complicated by the onset of recall urticaria (RU), characterized by delayed giant wheals at both current and previous injection sites. Laboratory findings suggested an inflammatory response, and the reaction was managed with corticosteroids and antihistamines, followed by colchicine, which achieved stable disease control. RU is a rare hypersensitivity phenomenon previously described with immunotherapy, heparin, NSAIDs, and other biologics, but to our knowledge, this is the first report associated with anakinra. This case broadens the spectrum of anakinra-related adverse effects and highlights the need for further investigation into the immunopathogenesis of RU.