Schnitzler syndrome is a rare, auto-inflammatory syndrome associated with IgM monoclonal gammopathy that manifests as a non-pruritic urticarial rash. Patients may also have intermittent fevers, lymphadenopathy, bone pain, and arthralgias. Given its rarity and nonspecific presentation, its diagnosis requires a high index of clinical suspicion. Herein, we describe a case of a patient with a 2-year history of urticarial rash who then developed fevers, arthralgias, neutrophilia, and weight loss. He was ultimately found to have a diagnosis of Waldenstrom Macroglobulinemia (WM)/Lymphoplasmacytic Lymphoma (LPL), in the context of Schnitzler Syndrome.
A 74-year-old traveling veteran presenting with fatigue, weight loss, arthralgias and rash was found to have anemia and leukocytosis concerning an occult hematologic malignancy. On exam, his rash appeared classically urticarial. He described the rash as nonpruritic and ‘waxing and waning’ for ~18 months. Following the rash, he developed drenching night sweats which progressively worsened over the last 4 months. This was accompanied by fatigue and arthralgias. On review of his labs, he had a normocytic anemia, thrombocytosis and progressive neutrophilia of approximately 20,000 over the last 4 months. Peripheral blood smear was remarkable for atypical lymphocytes. Peripheral blood flow cytometry revealed a small monoclonal CD5-/CD10- B-cell population of uncertain significance. His total serum IgM level was > 1000 mg/dL and serum protein electrophoresis with IFE confirmed a monoclonal IgM gammopathy with M-spike of 0.99 g/dL.
A bone marrow biopsy showed a hypercellular marrow with LPL comprising 50%-60% of the cellularity. It was also notable for grade 1/3 reticulin fibrosis and mild megakaryocytic aty WM/LPL can have a heterogeneous presentation. Urticarial rash, constitutional symptoms, joint pain, and neutrophilia should raise suspicion for Schnitzler syndrome, especially in conjunction with IgM monoclonal gammopathy. This rare syndrome is imperative to consider because it can be treated quickly with high efficacy with IL-1 antagonism. Anakinra is clinically effective for symptom management while awaiting primary treatment for underlying LPL.