Multiple myeloma, secondary AL amyloidosis: diagnostic challenges. A clinical case report

The article presents a clinical case of kidney amyloidosis associated with multiple myeloma (MM). The features of this clinical case include initially unverified nosological form of renal involvement with leading nephrotic syndrome. Amyloidosis is a group of diseases characterized by organ and tissue deposition of an abnormal fibrillar protein called amyloid that is not normally present. AA, AL, ATTR, and dialysis-related Ab2M amyloidosis are distinguished among systemic amyloidoses. One possible cause of AL amyloidosis development is MM. In patients with primary amyloidosis, plasma cell content in bone marrow is increased up to 5-10% (normally less than 4%; more than 12% in myeloma). Plasma cells produce a specific isotype of light immunoglobulin chains which predominate at immunohistochemical staining. Free monoclonal light chains of dominant lambda or (less frequently) kappa isotypes are detected in blood and urine but their level is lower compared to those in myeloma. Renal damage occurs in debut of MM in 50% of patients, with AL amyloidosis being found in 10-20% of cases. Initial clinical symptoms include weakness and weight loss; however, diagnosis is rarely made at this stage before organ symptoms appear. Amyloidosis may be suspected in patients with unexplained non-diabetic nephrotic syndrome-related proteinuria or unexplained edematous syndrome. Amyloid nephropathy manifests itself as proteinuria and has relentlessly progressive course culminating in severe nephrotic syndrome. This confirms our clinical case discussed below.