Hydropneumothorax as a Presentation of Birt-Hogg-Dubé Syndrome.

Birt-Hogg-Dubé syndrome (BHDS) is a rare genetic disorder characterized by cutaneous, pulmonary, and renal manifestations. We present a unique case in which a combination of multiple chronic illnesses, genetic testing, and significant family history led to a diagnosis of BHDS. A 72-year-old male patient presented to their primary care physician with a persistent cough of four months and was admitted to the emergency department after the discovery of a left hydropneumothorax. The patient's medical history was significant for recurrent spontaneous bilateral pneumothoraces diagnosed over 20 years ago, chronic obstructive pulmonary disease (COPD), and many other systemic illnesses. A combination of the patient's significant past medical and family history led to a diagnosis of BHDS. Genetic testing was also done to confirm the diagnosis. Despite benign skin lesions being the most common finding, they are not always present, as seen in our case, which can result in missed diagnosis. Due to the autosomal dominant nature of BHDS, it is vital to make an accurate diagnosis to allow for proper genetic counseling, as the development of renal cancer is the leading cause of mortality.