FLCN and Birt-Hogg-Dube syndrome: BHD- and FSP-associated folliculin mutations confer distinct clinical and histopathologic pulmonary manifestations, including recurrent, idiopathic pneumothoraces (typically at a young age of onset)[3,2,7,19] and numerous parenchymal lung cysts in atypical locations (extra-apical locations as compared to predominantly apical locations observed in idiopathic spontaneous pneumothorax)[8,7,20,12].