[A case of pulmonary Mycobacterium avium infection presenting multiple nodules with substantial difference in 18F-fluorodeoxyglucose uptake].

A 56-year-old man presented with a chief complaint of chronic cough due to bronchial asthma and pulmonary emphysema in 2001, without any abnormal findings on chest CT. His symptoms improved with high-dose inhaled corticosteroid. In February 2004, multiple nodules without bronchiectasis appeared in the chest CT. Pulmonary Mycobacterium avium infection was diagnosed by bronchial lavage and sputum culture. After multiple nodules appeared and disappeared repeatedly without medication, most nodules vanished after administration of antituberculous drugs. In Feburary 2007, a rapidly growing mass appeared in the right upper lobe, and a new nodule emerged in the left upper lobe the following month. On 18F-fluorodeoxyglucose positron emission tomography (18 FDG-PET), a substantial difference in 18FDG uptake was observed although both lesions were shown to be caused by Mycobacterium avium infection by needle biopsy. The lung specimen of the lesion with high 18FDG uptake demonstrated neutrophil infiltrates, suggesting acute inflammation. On the other hand, neutrophil infiltrates were not observed in the lesion with low uptake. We conclude that the degree of 18FDG uptake is not useful to decide when to initiate therapy and evaluate the efficacy of treatment.

[A case of lung adenocarcinoma with gradual enlargement of thin-walled cavity causing pneumothorax].

A 71-year-old man presented with a thin-walled cavity in his left lung in November 2006. A previous chest CT in 2003 showed a small thin-walled cavity in his left lingula. Although no obvious change was observed in 2004, the cavity increased its size from 11mm to 14mm in diameter and the wall became thicker in June 2006. On the first visit to our hospital in November 2006, the diameter of the cavity was 30mm and some part of the wall was thinner than on the previous CT. The patient developed pneumothorax one month later and underwent segmentectomy of the left lingula after unsuccessful thoracic drainage. Poorly differentiated adenocarcinoma was identified in both the pleura and the inner wall around the cavity. Lung adenocarcinoma with gradual enlargement of a thin-walled cavity causing pneumothorax has never been reported before. We report here the natural course of lung adenocarcinoma with a thin-walled cavity.

[Case of pneumothorax associated with pulmonary Mycobacterium fortuitum infection].

A 39-year-old man with dyspnea was revealed to have severe pneumothorax and received partial resection of the left upper lobe after unsuccessful drainage. Necrotizing epitheloid granuloma was found in the resected lung and Mycobacterium fortuitum was detected from the lesion. Chemotherapy with levofloxacin and clarithromycin was started one year after surgery because of the newly found nodular shadow near the lesion. The case experienced pyothorax due to pulmonary tuberculosis three years before and Mycobacterium avium pleuritis one year before this episode. Three-time mycobacterial pleural infection in three years seems to be uncommon. Furthermore this is the first report of pneumothorax associated with pulmonary Mycobacterium fortuitum infection.

[An autopsy case of invasive thymoma extending to the right atrium with superior vena cava syndrome as the initial manifestation].

We report a case of invasive thymoma presenting with superior vena caval obstruction and intracardiac extension. A 74-year-old man was admitted in July 2002 with swelling of the face and right upper extremity. Computed tomography of the chest revealed a small anterior mediastinal mass, which infiltrated the lumen of the superior vena cava extending into the right atrium. Invasive thymoma was strongly suspected, but he refused any medical treatment. His health declined steadily, with repeated right-sided heart failure. He died due to cardiac tamponade 50 months after his first visit. On autopsy, the tumor was diagnosed as a thymoma classified as type B3 according to the WHO histological classification. Formation of a tumor thrombus in the superior vena cava and the right atrium is a rare mode of extension of thymoma. In this respect, our case may be valuable for improving the understanding of the natural course of invasive thymoma.