Schnitzler's Syndrome: A Diagnostic Consideration in Evaluating the Constellation of Monoclonal Gammopathy and Chronic Urticaria

Schnitzler's syndrome is a rare clinical entity characterized by intermittent, non-pruritic urticarial rash, fevers, arthralgias, myalgias and monoclonal gammopathy, most commonly of the immunoglobulin M (IgM) subtype. Schnitzler's syndrome should be considered in the differential diagnosis of fever of unknown origin. We report a case of a 56-year-old healthy Caucasian female, who initially presented to the primary care physician's office with complaints of severe generalized fatigue and myalgias involving thighs and calves. Patient subsequently underwent extensive rheumatologic workup, and was treated with multiple courses of steroids with temporary resolution of symptoms. During the course of her workup she was found to have IgM kappa monoclonal gammopathy, and was referred to hematology for further evaluation. The constellation findings of fever, arthralgias, chronic intermittent non-pruritic urticaria, myalgias, and a negative rheumatologic workup in the presence of IgM monoclonal gammopathy raised the suspicion of Schnitzler's syndrome. Following completion of additional workup, she was started on anakinra 100 mg daily with prompt resolution of her symptoms. Due to the rarity of the disease, the diagnosis of Schnitzler's syndrome is often delayed, with an average time to diagnosis being approximately 5 years. The symptoms in most cases can be debilitating and add to significant morbidity as noted in our patient, who required bilateral hip arthroplasty at a much younger age than expected. Published reports discuss the poor quality of life associated with the delayed diagnosis and unawareness of potential end organ damage. With our case report we like to highlight the disease characteristics for an early identification to prevent further organ damage believed to be from chronic inflammation. Early diagnosis and treatment with agents such as interleukin-1 (IL-1) inhibitors can promptly provide symptomatic relief, reduce inflammation and prevent organ damage.