Is a collasped lung due to Marfan syndrome common?

Not Entirely Common. Marfan's patients can have spontaneous collapse of the lungs (known as pneumothorax). I would not say it is very common but it can occur. Typically marfan's patients have small air pockets at the top of the lungs called blebs. These blebs can rupture causing an airleak into the space between the lung and the chest wall. The air pushes on the lung causing the collapse.
Rare. Spontaneous pneumothorax is one of the less common features of marfan syndrome. Weakness of the connective tissue in the lungs can result in "blebs" in the lung, particularly in the apex of the lung. Blebs can rupture, leading to air leak out of the lung (pneumothorax), and subsequent collapse of the affected lung.

Related Questions

I'm looking for a really good orthotic insert for my shoes. Any recommendations? I have terrible flat feet due to Marfan syndrome.

Marfan or Marfanoid. flat feet: "Severe hindfoot valgus, also noted as medial deviation of medial malleolus (by clinical finding, not imaging)" is usually present, and treatment may be a matter of personal preference...Orthotics may be useful if pain is present. Custom-made soft orthotics may be needed to assure the proper fit essential for effective treatment." pdf download for orthopedic care found at marfan.org. Read more...