Diagnosis: This imaging presentation, in conjunction with a history of pneumothorax in a young patient, is consistent with Birt-Hogg-Dubé syndrome (BHD).

Teaching Points:

• Lung cysts in BHD typically manifest in early adulthood, and are lower lung predominant, often in a subpleural location or adjacent to interlobular septa. The cysts can be round, elongated or multiseptated. There is a 50-fold increase in the risk of spontaneous pneumothorax.
• Patients often present with multifocal, bilateral renal masse. The most common histologic subtypes include chromophobe oncocytoma, and chromophobe RCC; with less occurrence of clear cell RCC.
• Most patients with BHD exhibit skin lesions, characteristically fibrofolliculoma in the midface region.