Kidney Week

Abstract: PUB343

A Muddy Brown Presentation: A Case of Monoclonal Gammopathy of Renal Significance Associated with IgM Kappa Proliferative Glomerulonephritis with Monoclonal Immune Deposits and Leukocytoclastic Rash

Session Information

• Publication Only

Category: Glomerular Diseases

• 1402 Glomerular Diseases: Clinical, Outcomes, and Therapeutics

Authors

• Le, Cindy, University of Massachusetts Chan Medical School, Worcester, Massachusetts, United States

Cindy Le, MD

• Ge, Alex Yang, University of Massachusetts Chan Medical School, Worcester, Massachusetts, United States

Alex Yang Ge, MD

• Doppalapudi, Hima B., University of Massachusetts Chan Medical School, Worcester, Massachusetts, United States

Hima B. Doppalapudi, MD

• Vanguri, Vijay K., University of Massachusetts Chan Medical School, Worcester, Massachusetts, United States

Vijay K. Vanguri, MD

• Abramov, Konstantin, University of Massachusetts Chan Medical School, Worcester, Massachusetts, United States

Konstantin Abramov, MD

Introduction

Monoclonal gammopathy of renal significance (MGRS) is a diagnostic term, first introduced in 2012, used to describe patients who have renal disorders secondary to monoclonal gammopathies but who do not otherwise meet criteria for a hematologic malignancy. This case illustrates a unique presentation of proliferative glomerulonephritis (PGNMID) with IgM kappa immune deposits that presented with a leukocytoclastic rash.

Case Description

A 75-year-old man presented with hematuria, vomiting, and hematochezia. His serum creatinine was 3.78 mg/dL. Urine sediment showed muddy brown and granular casts initially attributed to acute tubular necrosis secondary to hypovolemia. He developed a leukocytoclastic rash. His renal function continued to decline requiring dialysis. Renal biopsy showed proliferative glomerulonephritis with monoclonal immune deposits. Hematologic workup identified an IgM kappa-producing B-cell clone, confirming a diagnosis of MGRS. He was treated with cyclophosphamide, bortezomib, dexamethasone, and rituximab, with resolution of his monoclonal paraprotein and recovery of his kidney function.

Discussion

Although not well studied, about 40-45% of patients with MGUS who underwent kidney biopsy also had MGRS-related disease. Furthermore, IgM kappa is a rare immunoglobulin class in PGNMID.The leukocytoclastic rash this patient presented with appears to be uncommon. It is unclear if there is a direct relation between this patient’s rash and MGRS. When association is suspected between monoclonal gammopathies and cutaneous manifestations, it would be expected that the immune complex deposits in the skin would be the same as the monoclonal gammopathy. However, the skin biopsy was positive for IgG but his kidney biopsy was positive for IgM. It is possible that clonal antigens from the patient’s B-cell clone triggered formation of immune deposits, which then deposited in the skin.