Mediastinal lymph node enlargement, especially anterior mediastinal lymph node enlargement, is the most common x-ray manifestation of Hodgkin's disease. That does not mean that that is your diagnosis – only that it should be considered in the differential diagnosis and, perhaps most important, that Hodgkin's disease is a treatable, curable disease. Whatever the cause of the lymph node enlargement, a tissue diagnosis will be required.
You should ask your doctor what diagnoses should be considered, given these CT findings and his/her recommendation of the least invasive diagnostic procedure likely to provide an accurate diagnosis. Depending on the distribution of the nodes, mediastinoscopy might be the procedure of choice. Fine-needle aspiration biopsy is generally considered inadequate for the diagnosis of Hodgkin's, but there are reports of percutaneous CT-guided biopsy being both useful and reliable. This decision should, to a large degree, be based upon the experience of your physicians.
Good luck.
I've had a chest CT last Friday that incidentally showed mild mediastinal adenopathy and enlarged subcarinal and paratracheal lymph nodes. I also have a 2.5 mm nodule in the RML of my lung. My PCP has referred me to a pulmonologist but that appointment is not until June 10. The answer posted for you has helped me somewhat and confirmed what search engines are pulling off the internet. My primary care physician told me today that he wanted to develop a banner for the search engines to display at the top of each page in large letters "IT MIGHT BE NOTHING!" I'm a nurse so that does not help things any. Sometimes we know just enough to scare us to death! Best of luck to you.