Birt-Hogg-Dubé Syndrome.

Birt-Hogg-Dubé (BHD) syndrome is a rare autosomal dominant disease caused by mutations in the folliculin gene, which encodes folliculin, a protein involved in several cellular processes, including growth and energy metabolism. BHD syndrome is characterized clinically by a triad of pulmonary cysts with increased risk of spontaneous pneumothorax; renal tumors, often with mixed histologic subtypes; and cutaneous fibrofolliculomas. Diagnosis is challenging and may require clinical examination, radiographic imaging, histopathological sampling, and genetic testing. Current management includes prompt pleurodesis for pneumothorax, serial imaging for renal tumor detection and surveillance, and screening relatives of index patients for BHD syndrome.