A 62-year-old Japanese man presented with high fever, cough, and sputa. Computed tomography (CT) scan of the chest revealed lung infiltrates with air bronchogram of the right middle lobe and mediastinal lymphadenopathy. Bronchoscopic examination was performed, and Mycobacterium avium complex was detected from bronchoalveolar lavage fluid. Although the administration of clarithromycin and levofloxacin improved the patient's symptoms, the lung infiltrates on chest CT scan gradually worsened. Lung biopsy of segments 4 and 8 by video-assisted thorachoscopy revealed angiocentric and angiodestructive massive lymphoplasmocytic Infiltrations with multinucleated giant cells, which were compatible with grade II angiocentric immunoproliferative lesions. The patient was found to have deterioration of renal function, and glomerular filtration rate was 32.6 mL/min. His kidneys were enlarged and showed prominent and diffuse uptake of gallium-67 citrate. Percutaneous renal biopsy revealed massive infiltration of CD4(+) mononuclear cells, plasma cells, and eosinophils in the interstitium and destruction of normal structure of tubules. Blood vessels were destroyed and replaced by inflammatory cells. The combination chemotherapy achieved a remission, and the patient has remained free of disease at 2 years after onset of the illness. We recommend the imaging of kidneys for diagnosis and following renal biopsy to evaluate the renal involvement of angiocentric immunoproliferative lesions. (C) 2002 by the National Kidney Foundation, Inc.