TABLE 2

Diagnostic criteria for Birt–Hogg–Dubé (BHD) syndrome

Diagnostic criteria proposed by Menko [58]
 Patient should fulfil one major or two minor criteria for diagnosis
  Major criteria:
   At least five fibrofolliculomas or trichodiscomas, at least one histologically confirmed, of adult onset
   Pathogenic FLCN germline mutation
  Minor criteria:
   Multiple lung cysts: bilateral basally located lung cysts with no other apparent cause, with or without spontaneous primary pneumothorax
   Renal cancer: early onset (age <50 years) or multifocal or bilateral renal cancer, or renal cancer of mixed chromophobe and oncocytic histology
   A first-degree relative with BHD
Diagnostic criteria proposed by Gupta [57]
 Definite pulmonary BHD:
  Characteristic# or compatible lung HRCT and skin biopsy positive for fibrofolliculoma or trichodiscoma
  Characteristic or compatible lung HRCT and confirmed family history of BHD in first- or second-degree family member
  Characteristic or compatible lung HRCT, and tissue confirmation or renal chromophobe adenoma or oncocytoma
  Characteristic or compatible lung HRCT, and tissue confirmation of genetic testing positive for BHD
 Probable pulmonary BHD:
  Characteristic HRCT, exclusion of TSC and LAM, and personal or family history of pneumothorax
  Compatible HRCT, exclusion of TSC and LAM, and any of the following:
   Family or personal history of renal tumours
   Skin angiofibroma
   Renal angiomyolipoma
 Possible pulmonary BHD:
  Compatible or characteristic HRCT

HRCT: high-resolution computed tomography; TSC: tuberous sclerosis complex; LAM: lymphangioleiomyomatosis. #: multiple thin-walled round, elliptical or lentiform, well-defined air-filled cysts, without internal structure, in a basilar, medial and subpleural predominant distribution, with preserved or increased lung volume, and no other significant pulmonary involvement (specifically no interstitial lung disease); : thin-walled cysts without the more typical elliptical shape or subpleural distribution.