Renal Amyloid Light Chain (AL) Amyloidosis Presenting With Anasarca

This case report discusses a 67-year-old male with a history of coronary artery disease, hyperlipidemia, and hypertension, but no known kidney disease, who developed renal AL amyloidosis. The patient presented with a one-month history of severe leg cramps, morning stiffness, and orthostatic hypotension. Initial labs showed elevated serum creatinine (1.3 mg/dL from a baseline of 0.88), low albumin (2.3 g/dL), low total protein, elevated ESR (75 mm/hr), and severe hyperlipidemia. Over the next few months, his kidney function deteriorated (creatinine rose to 3 mg/dL), and he developed generalized edema, massive proteinuria, and nephrotic features. Further testing revealed elevated serum free lambda light chains and an abnormal kappa/lambda ratio. A kidney biopsy confirmed AL-type renal amyloidosis with extensive immune deposits, acute tubular injury, and interstitial fibrosis. Immunofluorescence and electron microscopy supported the diagnosis, and serum immunofixation identified IgG lambda monoclonal proteins. Bone marrow biopsy showed 4% plasma cell involvement but no amyloid deposits. The patient was started on CyBorD chemotherapy (cyclophosphamide, bortezomib, dexamethasone) plus daratumumab. Cardiac workup showed mild diastolic dysfunction and MRI findings consistent with cardiac amyloidosis. Despite treatment, his kidney function worsened, and he required hemodialysis. He later underwent autologous stem cell transplantation.

Renal AL-amyloidosis is the extracellular deposition of amyloid protein fibril in the glomerular mesangium, arterioles, and tubules, causing nephrotic syndrome. It presents with kidney dysfunction and nephrotic range proteinuria. This case highlights the importance of early recognition and diagnosis of renal AL amyloidosis, as prognosis depends on disease stage and extent of organ involvement. Prompt referral, biopsy confirmation, and treatment initiation are essential to managing this progressive and often systemic disease.