Recurrent paraneoplastic nephrotic syndrome; insights from a Lynch syndrome patient with multiple malignancies.

Nephrotic syndrome is a common clinical presentation of glomerulopathy. A glomerulopathy as a paraneoplastic manifestation caused by underlying malignancy is rare. In patients with a solid tumor, membranous nephropathy is the most frequent paraneoplastic glomerulopathy. We present a case of recurrent paraneoplastic nephrotic syndrome caused by minimal change disease in a patient with Lynch syndrome. Over the years, a decrease in creatinine clearance and nephrotic-range proteinuria repeatedly functioned as a warning signal for underlying malignancies; consecutively, a colon adenocarcinoma, renal cell carcinoma and gastric adenocarcinoma were diagnosed. After treatment of the malignancies the nephrotic syndrome resolved without immunosuppressive therapy. Our patient also developed a primary lung carcinoma thrice, which did not cause an exacerbation of the minimal change disease. To further elucidate the mechanism behind the development of this phenomenon, we performed immunohistochemical analysis for vascular endothelial growth factor (VEGF) on the different tumor specimens. We found a high VEGF expression in the gastro-intestinal tumors, whereas the VEGF expression in the lung tumors was low, suggesting an association between VEGF expression and the development of paraneoplastic minimal change disease. This case report not only underlines the importance of considering a malignancy as a cause for (recurrent) nephrotic syndrome, especially in patients with an increased risk of developing malignancies like Lynch syndrome patients, but also suggests a role for VEGF in the pathogenesis of paraneoplastic minimal change disease.