A40-17 A Reexamination of Diagnostic Criteria of Birt-Hogg-Dube After First Presentation at Age Seventy-four

Abstract Introduction Birt-Hogg- Dubé syndrome (BHDS) is a genetic disease defined by triad of pulmonary, dermatologic and renal disease caused by germline autosomal dominant variants in the folliculin gene (FLCN), located on chromosome 17. The pulmonary disease is classified by lower lobe predominant cystic disease and spontaneous pneumothorax. Pulmonary disease is found in over 80% of families with germline variants. Current recommended diagnostic criteria define the disease presenting before the age of 40. Case Description 74-year-old man with tobacco use disorder presented to the emergency department with three weeks of dyspnea on exertion, found to have a pneumothorax on chest x-ray. He denied any trauma, travel, history of pneumothorax, or pulmonary disease. The patient was without children or siblings and was not aware of any family history of spontaneous pneumothorax or pulmonary disease. He was a current pack-a-day smoker with a forty cumulative pack year smoking history. A thoracostomy tube was inserted with improvement in symptoms. A CT chest was ordered to evaluate secondary causes of pneumothorax. Cross sectional imaging revealed bilateral lower lobe predominant pulmonary cysts. The physical exam revealed innumerable small 2-4 mm skin colored, dome shaped papules over the face, neck and chest. Given this constellation of symptoms, Birt-Hogg- Dubé syndrome was suspected. Genetic testing confirmed a germline mutation in the folliculin (FLCN) protein gene. The patient decided to forego surgical pleurodesis and instead underwent talc pleurodesis through his thoracostomy tube before discharge. The patient had CT scans of the abdomen that were negative for any renal malignancies. Case Discussion One of the parameters of the current recommended diagnostic criteria is multiple bilateral pulmonary cysts with lower lobe predominance with or without a history of spontaneous pneumothorax that develops prior to age 40. Unfortunately, the patient did not have previous imaging to compare, but conspicuously, this case highlights the vast difference in age of presentation compared to current recommended diagnostic criteria. We decided to undergo genetic testing because of the stereotypical constellation of symptoms despite the patient’s age. Our case demonstrates that patients with BHDS can present at advanced age, and until the genetic penetrance of the folliculin gene are better understood, BHDS should continue to be included in the differential for spontaneous pneumothorax or cystic lung disease despite age of presentation. This abstract is funded by: None