Birt-Hogg-Dubé Syndrome: A Rare Cause of Recurrent Spontaneous Pneumothorax

Abstract

Introduction: Birt-Hogg-Dubé syndrome (BHDS) is a rare autosomal dominant disorder characterized by cutaneous lesions, renal tumors and pulmonary cysts. Early recognition prevents complications and allow for timely detection of renal cancers. CASE PRESENTATION: 33 y/o male without significant past medical or family history presented to the ER complaining of chest pain & dyspnea. Chest x-ray showed a large right-sided pneumothorax. This was succesfully treated with chest tube placement, with no reaccumulation of the pneumothorax. He was discharged and referred for pulmonary evaluation. CT scan revealed the presence of bilateral pulmonary cysts. 3 weeks later, he was on a commercial flight when he experienced recurrent chest pain and dyspnea, prompting him to seek medical attention at a layover. Chest x-ray revealed a recurrent right-sided pneumothorax. He then underwent VATS pleurodesis. Genetic analysis revealed a heterozygous mutation in the FLCN gene, confirming the diagnosis of BHDS. Shortly after our patient was diagnosed, his sister suffered a spontaneous pneumothorax. It was recommended that she and other family members undergo genetic testing. DISCUSSION: BHDS is an autosomal dominant condition characterized by benign skin fibrofolliculomas, pulmonary cysts, spontaneous pneumothoraces and renal cancer caused by mutations of the FLCN gene. Approximately 200 families world-wide are known to have BHDS, though, as our case illustrates, it may be an under-recognized condition. Renal cancer is the most concerning complication with an estimated prevalence of 27%1. There are significant variations in cancer risk, due to different FLCN mutations. Ultrasonography can be an insensitive screening tool, so MRI is generally preferred. 89% of adults with BHDS have lung cysts. They tend to be basilar, in contrast to the apical predominance seen with emphysema. The risk of pneumothorax in BHDS is 50-times higher than that of the general population, with a prevalence rate of about 24%. Twenty three percent have had bilateral pneumothoraces. Untreated, the recurrence rate is approximately 75. Mechanical pleurodesis can significantly reduce the chances of recurrence2. Conclusions: BHDS is caused by mutations in the FLCN gene, characterized by skin fibrofolliculomas, pulmonary cysts, recurrent spontaneous pneumothoraces and renal cancer. Timely diagnosis is crucial to prevent complications.