Infection can induce hemophagocytic lymphohistiocytosis (HLH) and anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV). We herein report a 52-year-old man who had HLH and AAV simultaneously, possibly caused by Enterococcus faecalis infective endocarditis. The HLH diagnosis was based on the HLH-2004 criteria. AAV was diagnosed based on a positive result for proteinase-3 ANCA and necrotizing vasculitis of the small vessels on a skin biopsy. He eventually died and was sent for autopsy after combination treatment of valve replacement, antibiotics, and immunosuppressants, including corticosteroids. This case involved a challenging diagnosis and treatment of HLH with various complications in an adult.

Keywords： anti glomerular basement membrane antibody glomerulonephritis, Goodpasture syndrome, simple plasma exchange, Pneumocystis pneumonia, hemodialysis 〈Abstract〉 A 76 year old male with a history of total laryngectomy for laryngeal cancer and pulmonary adenocarcinoma was referred to our hospital with severe renal failure and anuria, which required urgent hemodialysis. Serological tests revealed strong positivity for the anti glomerular basement membrane (GBM) antibody ( ＞350 U/mL), leading to a diagnosis of anti GBM antibody glomerulonephritis. Although steroid pulse therapy and plasma exchange were performed, the patientʼs antibody titer always exceeded the upper limit of the detection range. As his renal function was not expected to improve, he was switched to maintenance dialysis, while the steroid dose was gradually reduced. Inhaled pentamidine was administered to prevent Pneumocystis pneumonia. After discharge, fever, bloody sputum, and elevated serum β D glucan levels were observed, and bronchoscopy revealed Pneumocystis pneumonia and diffuse alveolar hemorrhaging. The oral administration of trimethoprim/ sulfamethoxazole and corticosteroid therapy ameliorated the pneumonia and alveolar hemorrhaging, and additional plasma exchange reduced the patientʼs anti GBM antibody titer. In this case, a patient with high titer anti GBM antibody nephritis was considered to have developed alveolar hemorrhaging triggered by Pneumocystis