Unusual Case of Nephrotic Syndrome From Light Chain Amyloidosis in a 37-Year-Old Patient

Amyloidosis with renal involvement is a well-known cause of nephrotic syndrome. Immunoglobulin light-chain amyloidosis (AL), which is a result of monoclonal light-chain deposition in the kidney from plasma cell dyscrasia, is rare before the age of 40 and typically occurs in old patients. Most cases of renal amyloidosis in young patients are secondary to chronic inflammatory disease. We are reporting a case of a 37-year-old male who was transferred to our hospital for evaluation of possibly acquired bleeding disorder. He was initially presented to an outside hospital with bleeding per rectum for three days duration and one-week history of abdominal pain and bloating. He was found to have nephrotic range proteinuria with hypoalbuminemia and hyperlipidemia. A kidney biopsy was performed to identify the cause of his nephrotic syndrome, and a biopsy showed AL amyloidosis. Bone marrow biopsy performed showed plasma cell myeloma, and the patient was started on induction chemotherapy. Even though the incidence of AL amyloidosis is low before age of 40, we should always perform monoclonal gammopathy workup in patients with nephrotic syndrome regardless of the age. Prompt bone marrow biopsy should be performed to confirm the diagnosis, and starting the treatment as one of the factors that affect the prognosis of AL amyloidosis is early diagnosis.