My doctor found a "spot" on my lungs during a chest xray, and send me to a CT scan. The result came back as scar tissue (and previously unknown gallstones on the liver, but THAT's another story!) I have always been healthy, eat right, exercise, only been in a hospital to have babies, however I have been overweight for 25 years now (I'm 44) My parents were heavy smokers when I was growing up and I had a roommate for a couple of years that smoked though I personally never have. Other than that, I've only had a couple of bouts of bronchitis. What in the world could cause scar tissue?