Introduction: Cryoglobulinemic vasculitis presents as a systemic di- sease through vascular precipitation of immunoglobulins produced by clonal B cells mainly involving the skin, the kidneys and peripheral nervous system.Cryoglobulinemia is categorized into two main subg- roups:type I, which is seen exclusively in clonal hematologic diseases characterized by monoclonal immunoglobulins (Ig’s), usually of the IgG or IgM isotypes, and type II/III, which is called mixed cryoglobu- linemia consisting of polyclonal immunoglobulin (Ig)G with or wi- thout monoclonal IgM with rheumatoid factor activity and is seen in hepatitis C virus infection and systemic diseases such as B-cell lineage hematologic malignancies and connective tissue disorders.

Case Description: A 52-year old male patient without a known chro- nic disease applied to our clinic with complaints of high blood pres- sure and vomiting.His measured blood pressure was 180/95 mmHg. No other significant abnormality was found in his physical examina- tion.Notable laboratory findings were serum creatinine 1.2 mg/dl, 20 erythrocytes and 5 leukocytes on urine anaylsis, spot urine protein/ creatinine ratio of 1.2 gr/g, C3:31.3 mg/dl ( referance range: 90-180 mg/ dl ), C4:0.5 mg/dl (referance range: 10-40 mg/dl ), RF:31 IU/ml (referance range: 0-14 IU/ml ) and anemia (Hemoglobin: 10.6 g/dL). Hypocomple- mentemia and elevated levels of RF activity suggested mixed cryo- globulinemia.The cryoglobulin test was positive. Evaluation of under- lying cause revealed no infectious and autoimmune etiology. M spike was absent in protein electrophoresis, serum and urine immunofixati- on tests were negative. Peripheral blood smear examination showed no atypical cell formation.PET-CT detected no underlying malignan- cy.The presence of nephritic syndrome indicated for percutanous renal biopsy and membranoproliferative glomerulonephritis with exudative changes and intracapillary hyaline trombus formation was demonstrated in renal biopsy.Following bone marrow biopsy was compatible with low grade B cell non-Hodgkin’s lymphoma with IgM kappa type plasmacytic differentiation. BORID regimen ( Borte- zomid-Rituximab-Dexamethasone) was initiated.Patient was treated with intermittent dialysis due to hypervolemia and renal dysfunction. During every cycle of therapy,palpable purpura on lower extremities, increased hematuria, proteinuria and RF activity levels were detected after one week of Rituximab infusion.Rituximab associated flare of va- sculitis was considered and accordingly patient was started on Ibru- tinib therapy which resulted in stable remission.Follow-up imaging findings and bone marrow analysis showed no recurrence of disease.