"Overall do you agree with his assessment?"
Yes.
"Or do you think more looking into it should be done?"
Yes, but look for the real cause, which is not a cancer.
"I have no other signs of Marfans"
Then consider any CTD, such as Ehlers Danlos, which is associated with mystery conditions of the immune system.
"geneticist"
did they happen to find MTHFR?
Watch-and-wait is when a person is already known to have a cancer and the best approach is to do nothing, because the cancer is so slow growing that there is no need to undergo the possible harm from the treatment. So this is not watch-and-wait.
In your case, the odds that this is a cancer are very small and thinking about cancer just gets in the way. Here's what I'd suggest: set your mind instead to thinking about why your nodes behaved the way they did. That means you'd learn about how the immune system works, including about how and why fibrosis and/or granulomas happen. If you like, I'll look up a good intro lecture.
Understanding all about the most reasonable and likely (benign) explanation might be just the ticket to taking your mind off of jumping directly to the worst possible (cancer) explanation.
I'd only want a needle biopsy if the nodes started growing and didn't stop growing, or they started multiplying. So that's something almost like a watch-and-wait, except we wouldn't expect any of those two concerning signs to actually occur - we just want to be aware if they did occur.
"how slender I am"
Have you ever heard of Marfan Syndrome? If you look that up and think you might qualify, let me know.
Here's a start: https://www.marfan.org/about/signs
I would sincerely not want a surgical biopsy.
1) there's no reasonable suspicion that it's cancer
2) there is a very believable alternative cause: fibrosis
3) nodes have a useful purpose, they shouldn't be cut out without good reason
4) surgery always has risk. A famous example is that Joan Rivers died from a routine cosmetic surgery
However, you can ask for a needle biopsy, which mostly eliminates points 3 and 4. (But read a little on 'false negatives'.)
Your logical approach is very good throughout, Spartan. Here are some quick thoughts:
"family history of thyroid issues"
Then you are more likely than average to have various immune system problems. An infection can sometimes trigger autoimmune or autoinflammatory conditions. So whenever anything odd appears through the years, think of your immune system.
Maybe this episode was mono, from EBV. I personally believe that having an extra severe mono can mean one has a very reactive immune system.
"chest x-ray"
Probably were looking to rule out TB and sarcoidosis, which typically start in the lungs but can also make for nodes in the neck that are filled with granulomas (another possible cause of nodes that don't shrink back down).
"Doppler"
That looks for blood flow. Cancer makes new blood vessels to feed itself.
"came up overnight"
Cancer doesn't do that, then just stop. So that should be reassuring for you.
"virus"
It's possible that a virus acted to open the way for a bacterial infection in the lungs. The Abx defeated the bacteria but wouldn't kill any virus. It's somewhat possible, but not likely, that your system developed an autoimmune reaction to the Abx. Just be on alert to any rashes, etc., whenever you might take an Abx again. Remember the name of this Abx to correlate to the class of any future Abx.
There's still the very interesting delay, in that the virus didn't initially cause the fibrosis, neither the bacteria. Why is why I mention the Abx: the immune system detects the pathogen, then sets about experimenting over days with creating and testing different antibodies -- to best bind to the pathogen. Like making a series of progressively better keys to perfectly fit a complicated lock.
"i must emphasize they were not there prior to the illness"
Yep, you are very correct about saying that. We can go through some speculation on that if you like.
Hi, Spartan. I agree with the doc(s) who say that it is likely scarring (fibrosis). Usually, a node enlarges when immune cells inside multiply greatly, and then battle the invader (infection) outside the node. But think of your fibrosis as a buildup of rubble from when an immune battle happens right inside of a node.
Can you post the ultrasound report? We can see if it mentions anything troubling like calcification or cystic areas and so forth. (Probably it doesn't, though.) It was also Doppler, right?
I think we can sort of unify the 2 docs' opinions like this: tiny PacMans called macrophages have to take apart and take away the rubble, one brick at a time each. So it can take years, and seem like forever.
Yes, there have been more than a few like you who have come through this forum. Two very recent:
https://
www.medhelp.org/posts/Leukemia-and-Lymphoma-/Enlarged-lymph-nodes-for-months/show/3043130
https://
www.medhelp.org/posts/Leukemia-and-Lymphoma-/Swollen-Lymph-Node-for-10-months/show/3041824