What is Birt-Hogg-Dube syndrome?
Birt-Hogg-Dube syndrome (BHD) is a genetic condition caused by a change in the FLCN gene, which produces a protein called folliculin. It affects three main areas:
- Lungs: multiple thin-walled cysts, mainly in the lower parts of the lungs near the diaphragm and mediastinum, with a tendency to pneumothorax (collapsed lung).
- Skin: small, pale, dome-shaped bumps called fibrofolliculomas, usually on the face, neck and upper chest, appearing from the twenties or thirties.
- Kidneys: an increased risk of kidney tumours, which may be multiple and in both kidneys.
BHD is rare and probably under-diagnosed. Lung function is usually well preserved, which distinguishes it from other cystic lung diseases such as lymphangioleiomyomatosis and pulmonary Langerhans cell histiocytosis.
Symptoms
- Sudden chest pain and breathlessness from a pneumothorax, often the first sign, sometimes recurring or affecting both sides.
- No breathing symptoms at all in many people, with cysts found incidentally on a CT scan.
- Skin bumps on the face and neck that are harmless but may be cosmetically troubling.
- Kidney tumours, which are usually silent and found on screening, occasionally causing blood in the urine or loin pain.
A personal or family history of collapsed lungs, particularly when combined with skin lesions or kidney cancer, should raise suspicion.
Cause and inheritance
BHD is inherited in an autosomal dominant pattern: each child of an affected parent has a one-in-two chance of inheriting the gene change. Severity varies widely, even within one family, and some people have only lung or only skin features. Folliculin is thought to act as a tumour-suppressor and to influence how lung tissue responds to stretch, which may explain why cysts form where the lung is under most mechanical stress.
Smoking does not cause BHD but should be avoided, as it adds further lung damage.
How BHD is diagnosed
Many people with BHD are first seen with a pneumothorax that is wrongly labelled as simple primary spontaneous pneumothorax. A CT scan after a collapsed lung can reveal the typical cysts.
| Test | What it shows |
|---|---|
| High-resolution CT chest | Multiple, irregular thin-walled cysts predominantly in the lower and medial lungs, often next to vessels |
| FLCN genetic testing | Confirms the diagnosis and allows family members to be tested |
| Skin examination and biopsy | Fibrofolliculomas typical of BHD |
| Lung function tests | Usually normal or near-normal, which helps distinguish BHD from other cystic lung diseases |
| Kidney MRI | Screening for kidney tumours |
Other cystic lung diseases, including LAM, Langerhans cell histiocytosis, lymphocytic interstitial pneumonia and amyloidosis, are considered during assessment.
Treatment and management
Pneumothorax
A small pneumothorax may settle with observation, while a larger one needs aspiration or a chest drain. Because recurrence is common in BHD, a procedure to prevent further collapse (surgical pleurodesis or pleurectomy via keyhole surgery) is often recommended after the first episode, planned with thoracic surgery. More information is on the pleural disease page.
Kidney surveillance
Regular kidney imaging, preferably MRI, is recommended from early adulthood. Tumours found on screening are managed by urology, often with kidney-sparing surgery once they reach a certain size.
Skin lesions
Fibrofolliculomas are harmless. Dermatology can offer laser or other cosmetic treatments if desired, though lesions may return.
Flying and diving
Air travel is usually safe for people with BHD who have no current pneumothorax, but any new chest pain or breathlessness before or during travel needs assessment. Scuba diving is generally discouraged.
Outlook and family screening
Lung function usually remains stable and life expectancy is generally normal when kidney tumours are detected early. Long-term care is coordinated between respiratory medicine, thoracic surgery, urology, dermatology and clinical genetics. First-degree relatives are offered genetic counselling and FLCN testing so that those who carry the gene can begin kidney screening. Patients in Hyderabad are assessed at Apollo Hospitals, Financial District.
When to seek urgent care
Seek emergency care for sudden sharp chest pain, especially on one side, with breathlessness, as this may be a pneumothorax. Also seek urgent help for severe breathlessness, a racing heart, light-headedness or visible blood in the urine.
Frequently asked questions
Should everyone with a collapsed lung be checked for BHD?
Not everyone, but BHD should be considered when the lung collapses more than once, when there is a family history of pneumothorax, skin bumps or kidney cancer, or when a CT scan shows cysts.
Will my lungs get worse over time?
In most people with BHD, lung function stays near normal. The main lung problem is the risk of repeated pneumothorax rather than progressive breathlessness.
Can my children inherit BHD?
Yes. Each child has a one-in-two chance of inheriting the gene change. Genetic counselling and testing can be offered to family members.
How often should my kidneys be checked?
Regular kidney imaging, usually MRI, is recommended throughout adult life. The interval is decided by your specialists based on findings.
Can I fly if I have BHD?
Most people with BHD can fly safely if they have no current pneumothorax. Seek advice before flying after a recent collapsed lung or surgery.
Are the skin bumps dangerous?
No. Fibrofolliculomas are harmless. They can be treated cosmetically but are an important clue to the diagnosis.
Related conditions and procedures
Consult Dr. Gogineni Ratnakara Rao
Apollo Hospitals, Financial District: Monday to Saturday, 8:30 AM to 5:00 PM. Anything in Lung Clinic, Chanda Nagar: Monday to Saturday (Thursday closed), 6:00 PM to 9:00 PM.