What are some possible causes for a small mass found during a chest CT scan?

before I continue, I will be having this discussion with my doctor, but at the moment it is after hours

Last week I had a chest x-ray and a possible small nodule was found. A CT scan was ordered and I was just informed that a small mass was found and they need to order a PET scan. I’ll find out in the morning when the scan is, and this is when I’ll have a chance to ask more questions from my doctor. Until then I have a feeling I won’t be getting much sleep tonight.

Does anyone know what some possible causes are for a small mass found in the chest?

I’ve been experiencing shortness of breath. This is why the x-ray was ordered. My blood work didn’t show any problems.