C3 glomerulonephritis along with light chain proximal tubulopathy without crystal deposits in multiple myeloma: a case report

Abstract

Background Multiple myeloma causes different types of renal injury. C3 glomerulonephritis (C3GN) is characterised by an abnormal deposition of complement C3 in the glomeruli due to abnormal activation of the alternative pathway of the complement system. While the association between C3GN and multiple myeloma has been well established, mild renal injury by C3GN in multiple myeloma patients with high levels of light chain has not been reported. Case presentation A 55-year-old Chinese man presented with proteinuria. Combined with immunofixation electrophoresis, bone marrow biopsy, and renal biopsy, he was diagnosed with IgA-type multiple myeloma accompanied by C3GN and light chain proximal tubulopathy without crystal deposits. Although he had a higher level of lambda serum-free light chain, the renal injury in this patient was mild. After treatment with four courses of BD, one course of PAD, and autologous stem cell transplantation, he achieved a very good partial hematologic response with stable renal function. Conclusions In multiple myeloma, the light chain reaches a certain level and persists, resulting in C3GN renal impairment. Early diagnosis and early intensive treatment are critical for the prognosis of such patients.

Multiple Myeloma as a Potential Cause of Low Complements in Patients With Acute Kidney Injury

“…Traditionally, low complements in glomerular disease are associated with conditions such as MPGN, cryoglobulinemia, systemic lupus erythematosus (SLE), and post-infectious glomerulonephritis. However, there are very few reported cases of patients with low complements in the context of MM and renal failure [ 6 , 9 , 10 ]. Serological workup in our patient was negative for cryoglobulins, SLE, and human immunodeficiency virus, and, unfortunately, the patient did not allow us to perform a renal biopsy.…”

“…Abnormalities of complement activations in myeloma are not well understood besides conditions in MPGN and cryoglobulins. The defect in C3 activation and deposition, known as C3GN, likely plays a role in myeloma-related kidney injury [ 6 , 9 , 10 ]. The pathophysiology involves light chains binding to the complement regulator region of factor H, leading to abnormal activation of the alternative pathway of the complement system and subsequent abnormal deposition of complement C3 in the glomeruli, resulting in renal damage [ 6 , 9 , 10 ].…”

“…At a certain level, light chains can cause renal impairment due to abnormal deposition of complements [ 5 ]. The abnormal deposition of complements in the glomeruli can cause an abnormal activation of the alternative pathway of the complement system [ 6 ]. However, the association of hypocomplementemia with MM remains poorly understood besides cases of cryoglobulinemia.…”