What could "abnormalities" mean?

My sister had an MRI that came back and showed abnomormalities in the lungs, and now further testing is required.  I am hysterical because the doctor said she doesn't know what it is wihtout further testing, but that it is "very serious" and "we have a long road ahead of us".  They did a CT scan of the pelvis, stomach, chest, and head and we are awaiting results, but she said a biopsy is necessary.  I am trying to stay positive, but hearing her talk like that is discouraging.  When I asked some possibilities of these abnormalities, she didn't want to speculate. But then how can she say it is serious? I just want to have an idea to some of the possibilities.  Please help.  I am already imagining the worst.

[National Jewish Health]

I am sorry, but without more specific information about the alleged "abnomormalities in the lungs" it is not possible to even speculate what these abnormalities might be.  I agree with your question about how it can be "very serious" without an idea of what it may be.  The doctor who described the findings as "very serious" is surely well-intentioned but whatever this is, it can't be any worse than your fears of "the worst".  The doctor should be able to better describe the likely scenarios, if not to you, certainly to your sister.

Good luck.