My mother had MCTD, and eventually developed ILD as a complication of the overlap diseases. Not sure exactly which one caused the ILD (could have been SSc or Lupus or both). Unfortunately, my mother passed away from Acute Respiratory distress (an extreme result from the ILD). ILD is NOT terminal in every case; in fact, many cases associated with AI disease can be fairly mild. It is something that needs to be followed. My mother was diagnosed with it relatively late, and it was so out of control that the normal meds didn't help her much. There are better meds out there now to treat it. In fact, I've read that enbrel (and perhaps some of the other biologics) may play a role in preventing the progression of ILD (perhaps by decreasing inflammation in and around the lungs?).
Please know that I didn't tell you about my mother to scare you. She was an extreme case, and that result certainly doesn't happen to everyone with ILD. There can be some serious ramifications, though, if you didn't follow up with it. That's all. I don't currently have ILD--was assessed based on interesting scarring in my lungs, but I had a complete pulmonary work-up with a ct scan, so there is a good baseline to use if any changes should occur in my lungs in the future. Everyone, even those with no sx, should have a comprehensive physical including a pulmonary physical--especially with the high incidence of respiratory disease in this country.
Best of luck to you.
Current dx: Rheumatoid Arthritis
Suspected dx: UCTD/Lupus
Current Meds: Enbrel, Methotrexate, nexium, tramadol, nasonex, Nifedipine, Folic Acid, Tylenol PM