Crystalline Light Chain Casts and Hypercalcemia Induced Acute Kidney Injury: A Rare Presentation of Multiple Myeloma.

The most common cause of acute kidney injury (AKI) in multiple myeloma is light-chain cast nephropathy (LCCN), which consists of a light chain and Tamm-Horsfall protein (THP). We herein report a 46-year-old woman with hypercalcemia and AKI. A renal biopsy showed crystalline casts, which were consistent with lambda light chains but not THP. Hydration therapy and treatment to lower her serum calcium concentration were initiated immediately. She subsequently received bortezomib-based anti-myeloma therapy and recovered successfully. This was a rare case of LCCN, suggesting that hypercalcemia may play a role in the development of crystalline LCCN.

Fanconi Syndrome Associated with Long-term Treatment with Zoledronate.

Intravenous bisphosphonate therapy is used to prevent fractures in the management of bone metastasis. However, it may induce renal damage. We herein report an 81-year-old woman with Fanconi syndrome and osteomalacia who had been diagnosed with metastatic breast cancer and received treatment with zolendronate for over 5 years. Her bone markers normalized after switching zolendronate to denosmab and starting vitamin D and mineral supplementation. This case shows that chronic renal damage induced by zolendronate can cause osteomalacia. In patients with intravenous zolendronate therapy, close monitoring of renal and bone markers is needed, even under long-term therapy.

A man with immunoglobulin A nephropathy complicated by infection-related glomerulonephritis with glomerular depositions of nephritis-associated plasmin receptor.

A 27-year-old man who developed heavy proteinuria with hematuria and acute kidney injury 2 weeks after a fever was referred to our hospital. Because he had low complements without autoantibodies, we clinically diagnosed him with infection-related glomerulonephritis. The proliferation of mesangial cells and endothelial cells with glomerular deposits of immunoglobulin A and complement 3 was found. Deposition of glomerular nephritis-associated plasmin receptor, a marker of infection-related glomerulonephritis, was also found. In addition, the distribution of nephritis-associated plasmin receptor deposition almost perfectly matched the plasmin activity-positive region. Over 3 months later, his symptoms were resolved, although moderate proteinuria and active urine sediment were persistent. He underwent a second renal biopsy, and the histological findings revealed that he had immunoglobulin A nephropathy. Therefore, we diagnosed him with infection-related glomerulonephritis superimposed on immunoglobulin A nephropathy at the first renal biopsy. The glomerular deposition of nephritis-associated plasmin receptor is a useful marker and may cause worsening urinalysis findings after bacterial infection in cases of chronic glomerulonephritis.