Pulmonary cysts are a frequent clinical manifestation of Birt-Hogg-Dubé syndrome and are assumed to be the cause of pneumothorax in BHD patients (Johannesma et al. 2014f). Pneumothorax is when lungs collapse due to air leaking into the pleural cavity and in BHD patients the number of cysts is strongly correlated to the incidence of recurrent pneumothorax (Johannesma et al., 2014f). Since many lung diseases carry an increased risk of pneumothorax, it is hard to identify potential BHD cases when pulmonary symptoms present alone.
Takegahara et al. 2017, reports on a 40-year-old man who had experienced recurrent bilateral pneumothorax from the age of 22. At the time of this report, X-ray showed that the patient had a pneumothorax in his left lung, although it came to light that he had previously experienced three pneumothoraces on his right side. His case of pneumothorax did not subside following thoracostomy tube insertion and the decision was made to perform bilateral thoracoscopic surgery after a chest CT revealed the presence of cysts in both lungs. This enabled surgeons to remove the larger cyst suspected to be responsible for the problem, seal any lesions and performed a pleural covering with a polyglycolic sheet with the intention of reducing the recurrence of pneumothorax.
Despite the patient only exhibiting pneumothorax, clinicians suspected there to be an underlying genetic cause such as BHD, because of several observations including the patient’s family history of pneumothorax (mother and maternal grandmother). Subsequent genetic testing of the affected family members revealed a duplication mutation (c.1285dupC) in exon 11 of the FLCN gene, confirming them to be cases of BHD syndrome. Further examinations revealed no fibrofolliculomas or renal symptoms but long-term monitoring was recommended including for further pneumothoraces. Such a diagnosis is important because it can lead to early recognition and the better treatment of life-threatening BHD symptoms such as renal cell carcinoma, should they develop at a later age.