Lung Cysts

9 in 10 people with BHD will develop lung cysts. Cysts are sacs or holes inside the lung that are filled with air.

In BHD lungs can also have blisters known as “blebs” and “bullae”. Cysts and blisters in lungs are similar features of BHD, but they are medically different. They can form at the edge of the lung. When blebs are larger than 1cm (~0.4 inches) they are known as bullae. In this article we will refer to blebs and bullae as ‘blisters’.

BHD cysts and blisters do not normally affect how well your lungs function, but they can sometimes leak air causing the lung to deflate. This is called a pneumothorax, also known as a collapsed or punctured lung.

In a punctured lung, the amount of lung deflation can vary. You can have a smaller (partial) pneumothorax or a larger one. The size of the lung deflation is a factor in deciding what treatment you are given.

Cysts and blisters in the lungs can all cause a punctured lung. The number and size of lung features can vary from person to person, from none to dozens. They can all vary in size from a few millimetres to several centimetres.

However, there is no evidence to suggest that having more lung cysts and blisters mean you are more likely to have a punctured lung. You can have a single cyst and experience several punctured lungs over your lifetime. You can also have many cysts and blisters, and never experience a punctured lung.

To read more about pneumothorax symptoms and treatments you can see our Treatments and Symptoms pages.

• Published October 2023
• Clinically reviewed in July 2024 by Prof. Stefan Marciniak
• Date of next review July 2027