Mixed Cryoglobulinemia in the Setting of Monoclonal B-Cell Lymphocytosis and Monoclonal Gammopathy of Unknown Significance: A Case Report.

BACKGROUND Type II cryoglobulinemic vasculitis is a systemic syndrome that usually develops in the background of chronic HCV infection. Cases of non-hepatitis C (HCV)-related type II cryoglobulinemic vasculitis pose diagnostic and therapeutic challenges in patients with pre-existing hematologic and rheumatic conditions. CASE REPORT We present the case of an 82-year-old woman with a history of skin-limited hypocomplementemic urticarial vasculitis (HUV), monoclonal gammopathy of unknown significance (MGUS), and monoclonal B-cell lymphocytosis (MBL), with new-onset pericarditis, pleuritis, worsening rash, and acute kidney injury. Skin and renal biopsies confirmed a diagnosis of type II (mixed) cryoglobulinemic vasculitis. After an extensive infectious disease workup and an in-depth investigation on our patient's MGUS and MBL, none of the classic causative factors for non-infectious mixed-type cryoglobulinemia were identified. Ultimately, she was started on immunosuppressive treatment, despite which she experienced rapidly progressive disease with pulmonary involvement. Utilizing this case as a basis, we examine the challenges of treating non-HCV-related cryoglobulinemia in patients with complex medical histories. CONCLUSIONS We report a case of mixed cryoglobulinemia in the absence of infection and the presence of 2 premalignant hematologic disorders. Moreover, this case emphasizes the importance of conducting biopsies to differentiate between vasculitis syndromes with overlapping phenotypes, illustrates the diagnostic challenges of recognizing cryoglobulinemia in a timely fashion in patients with pre-existing hematologic and autoimmune comorbidities, and highlights the need for better prognostic and diagnostic methods.