Could taking accutane cause partially collapsed lung years later?

My 24 yr son had a partially collapsed lung (spontaneous pneumothorax) 2 months ago due to bleb on lung. Drs could not say why it happened. He took accutane 7 yrs ago for six mos, could this drug be the reason as some info online indicates there could be a link. He is tall and thin. Also could exercise cause this too? He was quite active before, lifting weights and doing chin ups, but has not been able to do any kind of exercise yet. Thx.