A Case of Primary and Secondary Membranous Nephropathy Associated with a Neuroendocrine Tumor

Introduction: Membranous nephropathy (MN) is one of the most common causes of nephrotic syndrome in adults. 80% of MN cases are of primary MN, while 20% are secondary. Primary MN involves a positive antibody for anti-phospholipase A2 receptor (PLA2R). Secondary MN is commonly a result of malignancy, infection or drugs. In this case, we present a patient with biopsy proven PLA2R MN and a new diagnosis of neuroendocrine tumor (NET) yielding a mixed primary and secondary MN diagnosis. Case Description: A 65 year old man with a medical history of congestive heart failure, chronic kidney disease and tobacco use presented with dark stools and altered mental status. His labs showed hemoglobin 6.4, potassium 8.4, BUN 194 and creatinine 8.9. A computed tomography of the abdomen and pelvis showed multiple enlarged lymph nodes concerning for malignancy. He underwent HD line placement and emergent dialysis was initiated. His mentation improved however his dark stools persisted. He underwent an esophagogastroduodenoscopy which showed an actively bleeding duodenal ulcer that was biopsied. Biopsy results showed a large-cell neuroendocrine tumor (NET). A renal biopsy was then performed which revealed PLA2R positive MN and severe acute tubular injury. Discussion: The simultaneous occurrence of primary and secondary MN in the setting of NET is rare with only a few cases reported in literature. This unusual presentation does not fit previously accepted classifications of primary versus secondary, but rather shows a combination. Therefore, concurrent workup for age appropriate cancer screening and serum PLA2R levels could be of benefit in patients with a new diagnosis of MN.IF staining of PLA2RThick basement membrane in MN