[Pulmonary mucosa-associated lymphoid tissue (MALT) lymphoma accompanied with cystic change].

A 64-year-old male with throat discomfort visited our hospital, and a chest computed tomography (CT) scan revealed a cystic lesion with a central solid component in the right lung (in the lower lobe, 4.1 x 3.9 cm in diameter). Transbronchial lung biopsy was performed and the lesion was diagnosed as mucosa-associated lymphoid tissue (MALT) lymphoma of the lung. No other lymphoma lesion was detected and it was diagnosed as the stage I-E, and a right lower lobectomy was performed. The cystic lesion derived from alveolus and bronchus destroyed by lymphoma infiltration and it might be caused by air retention due to check-valve mechanism.