[A case of thymoma and Mycobacterium intracellulare infection].

A 69-year-old man, who underwent total thymectomy 5 years previously, was referred to our division because the chest radiograph revealed abnormal shadows in both the lungs. The chest radiograph and CT scan showed pleural thickening in both apexes and tree-in-bud signs in both the lower lobes, which suggested bronchiolitis. We had retrospectively confirmed similar centrilobular small nodules and tree-in-bud signs on the chest CT scan when the thymoma was diagnosed. Mycobacterium intracellulare was detected in the sputum by acid-fast staining and polymerase chain reaction. The coincidence of thymoma and Mycobacterium intracellulare infection appeared to be incidental. Thus, in patients with thymoma, clinicians should carefully evaluate the lung parenchyma as well as the mediastinum on the chest radiograph to identify occult diseases, including Mycobacterium intracellulare infections.