June 11, 2019
A 57-year-old white male presents with fatigue, mild proteinuria, and a creatinine of 1.5 mg/dL. He was diagnosed with lymphoplasmacytic lymphoma 6 months ago, but refused treatment. Figures 1 & 2 show prominent pseudothrombi and a membranoproliferative pattern of glomerular injury. Image 3 shows moderate interstitial fibrosis. Image 4, 5, 6, & 7 show IgG, IgM, kappa, and lambda, respectively. This is a case of cryoglobulinemic glomerulonephritis secondary to lymphoplasmacytic lymphoma (Waldenström’s macroglobulinemia).
Waldenström’s macroglobulinemia is a rare B-cell lymphoma characterized by lymphoplasmacytic cell infiltration in the bone marrow and other organs and the presence of a monoclonal immunoglobulin M protein in the serum. Manifestations of the disease include neurological impairment (autoantibody to myelin-associated glycoprotein), hyperviscosity syndrome, lymphadenopathy, hepatomegaly, and/or splenomegaly. It is estimated that in 7-20% of patients the monoclonal protein has cryoglobulin properties which form pseudothrombi within the glomerular capillary lumens (images 1 & 2). Urinary Bence-Jones protein can be detected in 70% of patients. Over 90% of patients with Waldenström’s macroglobulinemia have a somatic mutation in the myeloid differentiation primary response 88 (MYD88) gene which enhances survival of neoplastic cells. 42% of patients with Waldenström’s macroglobulinemia have a 6q21 deletion. Treatment is recommended for symptomatic patients and for those with kidney involvement, such as plasma exchange and concomitant chemotherapy. Newer chemotherapeutic agents (Everolimus and Ibrutinib) have shown great promise for the treatment of this disease.