Possible familial case of Birt-Hogg-Dubé syndrome complicated with lung cancer: A possible link between these two disease entities.

A 65-year-old Japanese woman was introduced to our hospital for an examination of multiple pulmonary cystic lesions and a pulmonary nodule in the left lower lobe. She had a smoking history of 25 pack-years, and her two younger brothers had suffered from pneumothorax; one of them additionally had lung cancer with pulmonary multiple cystic lesions. A surgical biopsy specimen obtained from her left lower lobe revealed adenocarcinoma surrounded by a single epithelial layer that was covered with collagen fibers. The pathological features were compatible with the findings of the cystic lesions in the patients with Birt-Hogg-Dubé syndrome (BHDS). A diagnosis of BHDS was eventually made according to the detection of a folliculin gene mutation. This is the first report of a possible familial case of BHDS complicated with primary lung cancer. We herein reviewed the previously reported cases of BHDS with lung cancer and other tumors and discussed a potential mechanism of tumorigenesis and carcinogenesis in the lung in the patients with BHDS.