Clinicopathological features in membranous nephropathy with cancer: A retrospective single-center study and literature review.

BACKGROUND: Membranous nephropathy is the most common glomerular disease related to malignancy. However, it is difficult to distinguish between true malignancy-related membranous nephropathy and idiopathic membranous nephropathy coincident with cancer. It has been reported that phospholipase A2 receptor (PLA2R) is the first autoantigen involved in idiopathic membranous nephropathy and thrombospondin type-1 domain-containing 7A (THSD7A) may have a close relationship with malignancy-related membranous nephropathy. Therefore, the aim of this study was to compare the clinicopathological characteristics between membranous nephropathy patients with cancer and idiopathic membranous nephropathy patients without cancer to better detect malignancy-related membranous nephropathy, including glomerular PLA2R and THSD7A depositions and their circulating antibodies, together with glomerular IgG4 deposition. METHODS: Twelve membranous nephropathy patients with cancer and 257 idiopathic membranous nephropathy patients without cancer were included in this study and had been followed up for more than 1 year. The glomerular expression of PLA2R, THSD7A, and IgG4 was analyzed by immunohistochemistry. Circulating anti-PLA2R and anti-THSD7A antibodies were assessed by enzyme-linked immunosorbent assay and indirect immunofluorescence testing, respectively. RESULTS: Membranous nephropathy patients with cancer were significantly older and had higher serum creatinine and a lower estimated glomerular filtration rate than idiopathic membranous nephropathy patients (P<0.05). The positive rates of glomerular PLA2R and IgG4 depositions and circulating anti-PLA2R antibodies in membranous nephropathy patients with cancer were significantly lower than those in idiopathic membranous nephropathy patients without cancer (P<0.01). CONCLUSION: The absence of glomerular PLA2R deposition and negative circulating anti-PLA2R antibodies, along with negative glomerular IgG4 staining, may be useful clues to more accurately screen underlying malignancies in membranous nephropathy patients.