A Case of Mucus-producing Adenocarcinoma of the Lung with a 10-year Clinical History

A 63-year-old man was admitted to our hospital because a pulmonary mass with a 10-year history had enlarged rapidly in recent years. Chest X-ray film on admission showed a large mass shadow in the right upper lobe. Bronchofiberscopy revealed a polypoid tumor with a smooth surface completely occluding right B2. Right pneumonectomy was carried out as the histological findings of the biopsied specimen strongly suggested mucus-producing adenocarcinoma. Macroscopically, this well-circumscribed tumor contained abundant mucus. Microscopically, mucus-filled cyst walls consisted of mucus-secreting columnar cells. The pathological findings of the tumor resembled the mucinous cystadenocarcinoma originating in the ovary. Ultrastructure of the tumor showed a basal body in the cytoplasm. The tumor cells were weakly positive for lysozyme and negative for lactoferrin. These facts suggested that this tumor was derived from goblet cells rather than the bronchial gland.