A 82-year-old man was found to have mucinous bronchioloalveolar carcinoma associated with a cavity 10-cm in size in the right lower lobe, and he underwent a surgical lobectomy in April 2005 (pT2N0M0). Seven months after the surgery, chest images showed multiple metastases with thick-walled cavities in bilateral lung fields. The serial HRCT showed that thick-walled cavity lesions transformed into thin-walled cystic cavities associated with decreasing serum CEA levels. The patient's condition was good with best supportive care for 24 months from the time of recurrence. Subsequent progression of the thick-walled cavities into thin-walled cavities, was acompanied by re-elevation of serum CEA levels, and he died of respiratory failure 5 months after re-exacerbation. Macroscopic findings at autopsy showed multiple cavities in both lungs. Microscopic findings of the right lung showed desquamative mucinous bronchioloalveolar carcinoma cells lining the thick-walled cavity surface, and a single layer of tumor cells proliferating in the thin-walled cavity surface. Tumor cells with excessive mucus and necrosis were observed in the thick-walled cavities. It is suggested that thick-walled cavities were formed as a result of avascular necrosis and destruction of the pulmonary alveoli by excessive mucus, and thin-walled cavities were formed as a result of a check-valve mechanism.