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Abstract: SA-PO050

A Rare Case of Light Chain Cast Nephropathy, Light Chain Proximal Tubulopathy, and Crystal-Storing Histiocytosis in a Patient With Multiple Myeloma

Session Information

Category: Acute Kidney Injury

  • 102 AKI: Clinical‚ Outcomes‚ and Trials

Authors

  • Bui, Albert, Mayo Clinic Minnesota, Rochester, Minnesota, United States
  • Duriseti, Parikshit, Mayo Clinic Minnesota, Rochester, Minnesota, United States
  • Fidler, Mary E., Mayo Clinic Minnesota, Rochester, Minnesota, United States
  • Gilani, Sarwat, Mayo Clinic Minnesota, Rochester, Minnesota, United States
  • Gregoire, James Robert, Mayo Clinic Minnesota, Rochester, Minnesota, United States
Introduction

We report a rare case of combined light chain (LC) cast nephropathy, LC proximal tubulopathy (LCPT) and crystal-storing histiocytosis (CSH) in a patient with multiple myeloma (MM).

Case Description

A 58-year-old female presented with several days of nausea, anorexia, weakness and on evaluation was found to have serum creatinine of 14.2 mg/dL, hemoglobin of 8.1 g/dL, and serum calcium of 13.2 mg/dL. She was diagnosed with MM/plasma cell leukemia in the context of IgA λ-monoclonal protein with circulating λ-restricted plasma cells, bone lytic lesions on skeletal survey, 80-90% marrow plasma cell infiltration, and λ-free light chain of 2850 mg/dL. A kidney biopsy revealed λ-LC cast nephropathy, crystalline LCPT and CSH. IF noted diffuse granular tubulointerstitial staining with λ-LC without distinct localization to the tubular or glomerular basement membranes. There was no accompanying staining with κ-LC. CD68 stain was positive in interstitial cells confirming large number of histiocytes/macrophages with crystals. EM confirmed numerous intratubular casts and intracytoplasmic needle-shaped and rhomboid crystals with similar crystals within interstitial histiocytes. For acute kidney injury, she required initiation of dialysis. She underwent plasmapheresis for 7 days for cast nephropathy and started chemotherapy with CyBorD. She remained dialysis-dependent at 3-month follow-up.

Discussion

Multiple myeloma (MM) is characterized by clonal plasma cell proliferation and is defined by 10% or more bone marrow plasma cells and one or more of myeloma-defining events (hypercalcemia, renal insufficiency, anemia, and bone lesions). About 15-20% of patients with newly diagnosed multiple myeloma present with severe renal insufficiency. The most common MM-related kidney disease is light chain cast nephropathy (LCCN) resulting from co-precipitation of immunoglobulin free light chains with Tamm-Horsfall glycoproteins. Rarely, paraproteins can crystallize within proximal tubular cells (crystalline LCPT) or interstitial histiocytes (CSH). LCCN, LCPT and CSH occurring together in MM as seen in our case is extremely rare. Other unique feature of our case was λ-restricted crystalline LCPT and CSH (majority of cases reported in the literature of crystalline LCPT and CSH are κ-restricted).