Birt-Hogg-Dubé syndrome
Birt-Hogg-Dubé syndrome or folliculin gene-associated syndrome is a genetic multisystemic disease mainly characterized by:
- multiple lung cysts and secondary spontaneous pneumothoraces
- multiple bilateral renal tumors (particularly chromophobe renal cell cancer and oncocytoma)
- cutaneous manifestations (angiofibromas, perifollicular fibromas, acrochordons, fibrofolliculomas, etc.)
Epidemiology
Birt-Hogg-Dubé syndrome carries an estimated 25% risk of renal cell carcinoma .
Pathology
Genetics
Deletion mutation in the folliculin (FLCN) gene (short arm of chromosome 17), with autosomal dominant inheritance.
Radiographic features
CT
Lung cysts in Birt-Hogg-Dubé syndrome are usually multiple and have a lower zone predominance . Cyst morphology tends to be variable within each patient, with cysts commonly oval or lentiform and septated when large . The presence of paramediastinal cysts when disproportionate in number or oval (floppy) in shape is another distinguishing characteristic .
History and etymology
It is named after A R Birt, G R Hogg and W J Dubé who published their findings in 1978 .
Differential diagnosis
Consider other cystic lung conditions such as:
- lymphangioleiomyomatosis
- cysts typically round, with diffuse (rather than lower zone) distribution
- Langerhans cell histiocytosis
- cysts variable in shape but classically co-existing with cavitating nodules. There is upper and mid zone predominance in size and number of cysts with sparing of costophrenic angles in contrast to lower lobe predominance in Birt Hogg Dube syndrome.
- lymphocytic interstitial pneumonitis
- co-existing ground-glass opacity and other parenchymal change
- desquamative interstitial pneumonia
- co-existing ground-glass opacity and other parenchymal change