Anti-neutrophil CytoplasmAntibody-Associated Vasculitis as Paraneoplastic Glomerular Disease

Introduction: Paraneoplastic glomerulonephritis (PGN) is a rare complication of a malignant tumor, with glomerular lesions induced by products of tumor cells. ANCA-associated vasculitis (AAV) occurs in 14-20% of paraneoplastic syndromes associated with renal tumors; 71% are clear-cells carcinoma. In Latin America there are no cohorts that evaluate the association of AAV and renal cell carcinoma. Case Description: CASE 1: 51 years old male, admitted requiring KRT. We found active urinary sediment and positive anti-MPO. An image of a kidney tumor was found in the echography, later confirmed with CT. Patient had a partial nephrectomy, with pathology result showing clear cell renal cell carcinoma and pauci-immune crescentic glomerulonephritis with focal and segmental sclerosis and grade II interstitial fibrosis. CASE 2: 56 years old male, admitted due to uremic syndrome, and behavior of rapidly progressive glomerulonephritis, starting KRT. We found positivity for anti-MPO, evidence of a kidney tumor in echography and TC. A renal biopsy was performed, reporting active pauci-immune crescentic glomerulonephritis and grade II interstitial fibrosis. He was treated with complete nephrectomy four months later, pathology confirmed clear cell renal carcinoma. CASE 3: 44 years old male, with granulomatosis with polyangiitis since 2020, referred because of proteinuria and chronic kidney disease. Ecography showed a renal tumor, CT was performed suggesting clear cell renal carcinoma. Discussion: The course of PGN is a rare diagnostic and a therapeutic challenge, so early identification and treatment with close follow-up could help improve the prognosis. It is reasonable to treat AAV with standard immunosuppression, including steroids and/or cyclophosphamide and/or rituximab, given the high associated morbidity and mortality, along with planned cancer treatment.