Any info on a collapsed lung, what's cause in 17 year old boy?

Trauma or bleb: Most common cause is a rib fracture that punctures the lung causing lung collapse from pneumothorax. Another cause is rupture of a bleb (an air filled blister on the surface of the lung) if enough air leaks out of the bleb, the lung collapses from pneumothorax. Depending on the size of the pneumothorax, a chest tube may need to be placed to remove the air leak and rexpand the lung.

Lung: A collapsed lung or pneumothorax can rarely occur spontaneously but usually related to trauma including multiple rib fractures following trauma.

Bleb: Non-trauma, spontaneous pneumothorax occur as a result of an abnormality in the lung tissue. The abnormality may be apparent in cases such as emphysema. Sometimes, they are not so apparent in the cases of small/tiny blebs or catamenial (females) pneumothoraces. Whatever the case, spontaneous pneumothorax is associated with 20+% recurrence rate.