Do BHD Lung Cysts Correlate with Collapsed Lungs?

A recent study has been published characterising lung cysts in a small group of Birt-Hogg-Dubé Syndrome (BHD) patients in China. The study examined the features of lung cysts to see if there was any relationship with having a collapsed lung (pneumothorax).

A total of 26 BHD patients from 11 families aged between 20 and 68 years were selected for the study. Just over half (14 out of 26 individuals) had experienced a collapsed lung. Nearly half of those (6 out of 14 individuals) had experienced a lung collapse between 2 and 4 times. None of the patients had any skin or kidney symptoms typical of BHD.

A lung CT scan was available for 23 of the individuals. In total, 2323 lung cysts were documented across the scans. The lung cysts ranged from 4 – 110 mm in diameter. The authors found a significant difference in some features of lung cysts between people who had a collapsed lung and those that didn’t. The size and volume of the largest cysts were bigger in people who had a collapsed lung. However, there was no difference in the number of cysts between the 2 groups.

One measurement, called the short-axis diameter, can often reflect the tension of the cyst. Imagine there are 2 cysts that have the same volume but differ in size so that one is long and thin and one is more round. The one that is more round has a bigger short-axis diameter and a higher tension and is more likely to burst.

There were some limitations of the study. Firstly, the sample size was small and secondly some individuals had a history of pneumothorax. This may have affected the characteristics of the lung cysts observed in this study. In the future, they would like to study more BHD patients to better observe the relationship of lung cysts and collapsed lungs.

The authors also spoke about the need for awareness of BHD among clinicians. They particularly mentioned emergency department doctors and surgeons. Individuals who experience a collapsed lung often go to emergency departments for treatment. Although the collapsed lung needs to be treated quickly, time should also be taken to investigate any underlying causes. Around 1 in 3 individuals with BHD get kidney cancer. Early diagnosis of BHD is important to recognize and treat any kidney cancer. The BHD Foundation works to raise awareness of BHD among clinicians. We have recently developed a leaflet dedicated to the symptoms of BHD that will prompt doctors to consider a BHD diagnosis.

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