Intrahepatocellular crystal storing mimicking a clinical liver disease during monoclonal gammopathy: report of a case and review of the literature

Types of M protein and clinicopathological profiles in patients with monoclonal gammopathy of renal significance

BACKGROUND

The development of renal disease in patients with monoclonal gammopathy of renal significance (MGRS) depends on the pathogenicity of the secreted monoclonal protein (M protein). However, the correlation between the types of M proteins and clinical and renal pathological features is still unclear.

METHODS

A total of 148 patients with detectable serum M protein and biopsy-proven MGRS were recruited. The patients were categorized according to the heavy and light chain types of M protein in the serum.

RESULTS

Among 148 patients, the most common M protein was IgGλ, followed by IgAλ and IgGκ. According to the type of heavy chain, patients with IgM-MGRS were more likely to have renal dysfunction, anemia and hypocomplementemia than patients with IgG-MGRS and IgA-MGRS. The λ light chain was predominant in patients with IgG-MGRS and IgA-MGRS, whereas the κ light chain was predominant in patients with IgM-MGRS. The most common renal lesion was amyloidosis in patients with IgG-MGRS and IgA-MGRS, while it was cryoglobulinemic glomerulonephritis in patients with IgM-MGRS. According to the type of light chain, patients with κ light chain were more likely to be male and to have renal dysfunction, anemia and hypocomplementemia than those with λ light chain. The types of heavy chain and light chain of M protein were not associated with patient or renal survival.

CONCLUSION

The clinicopathological features were distinct in patients with different types of M protein. Integration of the types of M protein and renal pathologic findings may shed light on individual management of patients with MGRS.