A 40-year-old man, diagnosed with Addison's disease 2 years before, presented with a 1-month history of intermittent fever and no other relevant symptoms. His physical examination revealed no abnormalities. A haemogram, a routine biochemistry profile and coagulant tests were all normal, except for an erythrocyte sedimentation rate of 70 mm/hour. Radiographs of the chest and abdomen and an echocardiogram were unhelpful. Brucella spp serology and blood cultures were negative. Mantoux (5 UI) was 12 mm. Ziehl-Neelsen stain and mycobacterial urine cultures were negative, as was a bone-marrow culture for Mycobacteria and Brucella. An abdominal computer tomography (CT) scan showed a hypodense mass in the right lobe of the liver and an enlarged right adrenal gland with calcifications. Fine-needle aspiration of the liver was negative for malignant cells. Microscopic examination of stained specimens revealed no acid-fast bacilli or other microorganisms, and cultures (aerobic and anaerobic) for bacteria and fungi were negative. Laparotomy was performed, obtaining purulent material from the adrenal gland, with extension to the liver and duodenum. Gram and Ziehl-Neelsen stains of the pus were negative, but Streptococcus constellatus was isolated in pure culture, using the API 20S system. The minimum inhibitory concentration (MIC) for penicillin was 0.03 microgr/ml. Microscopic examination revealed granulomas in the liver and adrenal tissue. The patient was treated with ceftriaxone, rifampicin, isoniazid and pyrazinamide, and his condition improved. Lowenstein culture of the abscess material yielded positive result for Mycobacterium tuberculosis.