Case Report Lymphoma-Associated Monoclonal Cryoglobulinemic Glomerulonephritis and Relationship with Hepatitis C Virus Infection: A Case Report Sangeeta Mutnuri , 1 Hania Kassem, 1 John Badalamenti, 1 You-Wen Qian, 2 Christopher Marquez , 2 and Marjan Afrouzian 1,2 1 Department of Internal Medicine, University of Texas Medical Branch, Galveston, TX, USA 2 Department of Pathology, University of Texas Medical Branch, Galveston, TX, USA Correspondence should be addressed to Marjan Afrouzian; maafrouz@utmb.edu Received 21 May 2019; Accepted 17 July 2019; Published 18 August 2019 Academic Editor: David Mudge Copyright © 2019 Sangeeta Mutnuri et al. Tis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. We report a case of type I cryoglobulinemic glomerulonephritis in a patient with chronic hepatitis C who presented with acute renal failure. Te renal biopsy revealed membranoproliferative GN (MPGN) due to cryoglobulinemia with unexpected monoclonal Kappa restriction on immunofuorescence microscopy, suggesting an underlying hematopoietic malignancy. Te bone marrow biopsy revealed presence of marginal zone lymphoma. Our case raises awareness regarding possibility of monoclonality in the renal biopsy of HCV-infected patients and exemplifes the crucial role the renal biopsy plays in detecting lymphoid malignancies where clinical features are ambiguous. 1. Introduction Monoclonal (type I) cryoglobulinemic glomerulonephritis (mCGN) is an uncommon diagnosis, usually reported in association with lymphoproliferative malignancies [1]. Hep- atitis C virus (HCV) infection-associated cryoglobulinemia, on the other hand, is a much more common disease, expected to afect the kidney by causing polyclonal (type II) cryo- globulinemic glomerulonephritis (pCGN) [2]. Herein, we introduce an HCV-infected patient who presented with renal failure and in whom the renal biopsy revealed cryoglobu- linemic glomerulonephritis (CGN) with monoclonal light chain restriction. Te incidences of pCGN and mCGN are compared and the importance of detecting monoclonality in the renal biopsies obtained from HCV-infected patients is entertained. 2. Case Report 2.1. Clinical History and Initial Laboratory Data. A 47- year-old Caucasian male with a history of HCV infection (genotype 3A) and hypertension was admitted with com- plaints of shortness of breath, dyspnea on exertion, lower extremity edema, abdominal distention, and decreased urine output for the past two months. Physical examination revealed an elevated jugular venous pulse to 8-10 cm of water, bibasilar crackles, an S3 gallop, bilateral lower extrem- ity edema, and hepatosplenomegaly. He was hyperten- sive with a blood pressure of 183/111 mmHg. Laboratory tests revealed pancytopenia, hypoalbuminemia, hypocom- plementemia, cryoglobulinemia, elevated HCV PCR levels, an elevated creatinine level, and an elevated rheumatoid factor level (Table 1). Urine microscopy revealed dysmorphic red blood cells (RBC) in addition to white blood cell (WBC) and RBC casts. He was also found to have nephrotic range proteinuria (9.5 g in 24 hours). Retroperitoneal ultrasound only showed a small vol- ume of ascites, 14 cm and 12 cm sized kidneys with no hydronephrosis. HCV-induced cryoglobulinemia was sus- pected and a kidney biopsy was performed. Hindawi Case Reports in Nephrology Volume 2019, Article ID 7940291, 5 pages https://doi.org/10.1155/2019/7940291