[A case of pulmonary MALT lymphoma with 6-year natural history]

A 58-year-old asymptomatic man was referred for investigation of an abnormal shadow on chest X-ray films. Chest computed tomography (CT) revealed an infiltrative shadow containing an air-bronchogram. Video-assisted thoracic surgery was performed for a lung biopsy of an abnormal region in the right upper lobe of the lung. Based on immunohistochemical examinations and gene analysis, the abnormal shadow was diagnosed as primary pulmonary B-cell lymphoma of mucosa-associated lymphoid tissue, t(11; 18)/API2-MALT1. Rituximab-CHOP therapy yieled a complete response. He had abnormal shadows on chest X-ray films in both lung fields since 6 years previously. Retrospective examination of chest radiographs revealed slow growth during the 6 years.