[A case of secondary lung cancer of cystadenocarcinoma showing multiple thin-walled cavities]

A 74-year-old woman was admitted to our hospital with the complaint of general fatigue. Chest X-ray revealed multiple thin-walled cavities in both lung fields. Cystadenocarcinoma in the liver and secondary lung cancer were diagnosed on the basis of chest X-ray, abdominal CT, and lung biopsy. She died of respiratory failure, in spite of treatment with chemotherapy for 8 months. At autopsy, the liver mass was diagnosed as cystadenocarcinoma, which had developed from a benign cystadenoma with the capacity to produce mucinous material. Thin-walled cavities in the lungs showed the same histological findings. Therefore, the mechanism of cavity formation in this case was speculated to have been metastasis of mucin-producing cystadenocarcinoma, with entry of air secondary to communication with the terminal bronchiole.