AP-VAS 2012 case report: a case of ANCA-negative pauci-immune crescentic glomerulonephritis associated with IL-6-producing adenosquamous cell carcinoma of the lung.

A 76-year-old man with lung cancer and multiple metastases was admitted for purpura and rapidly progressive glomerulonephritis. Adenosquamous cell carcinoma of the lung had been diagnosed 6 months earlier. Two anti-cancer drug regimens had no effect. At admission, his survival with his malignancy was estimated to be several months. Renal biopsy revealed pauci-immune necrotizing crescentic glomerulonephritis (CrGN). Negative results were obtained for myeloperoxidase-anti-neutrophil cytoplasmic antibody (ANCA) and proteinase-3-ANCA by enzyme-linked immunosorbent assay, and for peripheral-ANCA and cytoplasmic-ANCA by indirect immunofluorescence. He was diagnosed with ANCA-negative pauci-immune CrGN. Although steroids were initiated, the patient died of renal failure and intestinal bleeding 2 weeks later. It was later found that cancer cells were positive for interleukin (IL)-6 and that serum IL-6 levels were significantly elevated, concomitantly with increased IL-8, granulocyte-colony stimulating factor and transforming growth factor-β levels. Some kinds of lung cancer are known to produce IL-6 that activate neutrophils and are related to ANCA-associated CrGN. It appears that IL-6 can activate neutrophils in the pathogenesis of ANCA-negative pauci-immune CrGN with lung cancer. Therapy that blocks IL-6 may prove to be effective in vasculitis and cancer-related symptoms in such cases.