Membranous nephropathy concurrent with renal amyloidosis: a six-patient report and literature review.

The KDIGO 2021 guidelines suggest that individuals who test positive for serum anti-phospholipase A2 receptor (anti-PLA2R) antibodies may not require a renal biopsy to establish a diagnosis of membranous nephropathy (MN). However, it is imperative to acknowledge that MN can coexist with other chronic kidney diseases. In instances where MN is comorbid with IgA nephropathy, diabetic nephropathy, or focal segmental glomerulosclerosis, the therapeutic approach tends to be analogous. Nevertheless, there is a significant disparity in both the treatment regimen and the prognosis between MN and renal amyloidosis, with variations existing even among distinct subtypes of renal amyloidosis. Given that both MN and renal amyloidosis exhibit a predilection for the geriatric population, it is prudent to consider the possibility of MN concurrent with renal amyloidosis in elderly patients who test positive for serum anti-PLA2R antibodies. This consideration should precede a straightforward MN treatment strategy. In this report, we present six patients with MN concurrent with renal amyloidosis identified at our center over the past 14 years; in five of whom were positive for serum anti-PLA2R antibodies. We further elucidated the divergent clinicopathological characteristics and prognostic implications of these cases.