Birt-Hogg-Dubé syndrome detected incidentally by asymptomatic bilateral pneumothorax in health screening: a case of a young Japanese woman

Birt-Hogg-Dubé syndrome (BHD) is an autosomal dominant disease caused by mutations of germline folliculin (FCLN) mapped in the chromosome 17p11.2 region. BHD commonly accompanies renal tumors, fibrofolliculomas, multiple pulmonary cysts, and spontaneous pneumothorax. We report a case of a young Japanese woman in whom asymptomatic bilateral pneumothorax was found incidentally in a health screening, which led to the diagnosis of BHD. She had developed neither renal tumors nor fibrofolliculomas. However, her father, uncle, and aunt also experienced pneumothorax. In Japan, BHD is not yet well known because skin-related symptoms of fibrofolliculomas are sometimes absent unlike in most cases in Europe and the United States. On the basis of this case, we propose that BHD should be considered at the time of pneumothorax examination.