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Abstract: SA-PO200

Triple Monoclonal Protein-Related Kidney Lesions in a Patient with Plasma Cell Dyscrasia

Session Information

Category: Onconephrology

  • 1700 Onconephrology

Authors

  • Alvi, Arsalan Ahmad, University of Minnesota Twin Cities Division of Nephrology and Hypertension, Minneapolis, Minnesota, United States
  • Gallan, Alexander James, Department of Pathology, Medical College of Wisconsin, Milwaukee, Wisconsin, United States
  • Klomjit, Nattawat, University of Minnesota Twin Cities Division of Nephrology and Hypertension, Minneapolis, Minnesota, United States
Introduction

Toxic monoclonal protein typically results in a single type of kidney pathology due to biophysical properties of monoclonal protein. Multiple type of lesions is rarely reported. We report a patient with monoclonal gammopathy who has light chain cast nephropathy (LCCN), light chain proximal tubulopathy (LCPT) and thrombotic microangiopathy (TMA).

Case Description

A 57-year-old male with history of dermatomyositis and sarcoidosis on mycophenolate mofetil and prednisone who presented with fever, nausea, and loose stool for 3 days. He was diagnosed with concealed ruptured diverticulitis. He had a baseline creatinine (Cr) of 0.8-1.0 mg/dl but it was 1.47 mg/dl 3 months ago. Upon presentation, Cr was 2.81 mg/dl which continued to rise and peaked at 9.29 mg/dl requiring hemodialysis. Platelet (Plt) and Hemoglobin (Hb) were normal upon admission but continued to decrease along with the presence of hemolysis marker. ADAMTS13 activity was 28%. Kappa light chain (LC) of 16 mg/dl and kappa lambda (K/L) ratio of 7.17. Serum electrophoresis showed IgG kappa with M- spike of 0.2 g/dl. His urine analysis showed blood and granular cast, and his protein to creatinine ratio of 1.33 mg/mg. He underwent a kidney biopsy which showed kappa LCCN, TMA and non-crystalline LCPT with minimal interstitial fibrosis. Bone marrow biopsy showed less than 3% of kappa-restricted plasma cell. Complement study showed elevated sC5b-9. Given the finding of progressive TMA, he underwent plasma pheresis for 3 sessions as a bridging therapy before initiating anti-plasma cell therapy with daratumumab, bortezomib and dexamethasone. Due to recent infection, eculizumab was on hold. After the 1st cycle, he is still dialysis dependent but kappa free light chain came down to 3.83 mg/dl with K/L ratio 1.32. Hb and Plt improved but still has positive hemolysis marker so the plan is to start Eculizumab and continue chemotherapy.

Discussion

This case highlights the importance of toxic properties of monoclonal protein in causing kidney diseases. Triple monoclonal protein related kidney lesions can occur but rare. LCCN is a myeloma defining event but his LC (<50 mg/dl) and plasma cell burden is low (<10%) which makes this case very unusual. Sepsis-induced low flow stage may induce LCCN in this patient. Aggressive therapy is likely needed to eradicate the clone in order to achieve organ response.