Paraneoplastic Seronegative Pauci-Immune Glomerulonephritis Associated with Lung Adenocarcinoma Responds to Rituximab: A Case Report

Anti-neutrophil cytoplasmic antibodies (ANCA) play an important role in the pathogenesis of pauci-immune renal vasculitis. However, in 10% of the cases, ANCA are absent. We present a case of a 64-year-old man with a chronic untreated hepatitis C virus infection and Middle Eastern thalassemia who was ANCA-negative when he was hospitalized due to acute kidney injury and accounts for an uncommon presentation of renal vasculitis. The patient had earlier reported to have undergone local lobectomy and adjuvant chemotherapy (carboplatin/pemetrexed) for lung adenocarcinoma a month prior. IL-6 has been reported to be involved in the pathophysiological cascade causing pauci-immune glomerulonephritis amongst non-small cell lung cancer patients. Previous studies with subgroup analysis have demonstrated that ANCA negativity has been associated with more chronic glomerular lesions and less crescent formation, which tends to have a critical outcome in the renal system. However, our patient underwent kidney biopsy exhibiting active crescentic glomerulonephritis, pauci-immune type with 5 cellular crescents amongst 15 glomeruli. To our knowledge, this is the third reported case of ANCA-negative vasculitis with typical presentation on biopsy in non-small cell lung cancer patients.