I have a friend who told me that a golfball-sized lump appeared on their neck literally overnight. I don't know the exact location, but they didn't mention any complaint of breathing or swallowing difficulty, and I'm sure they would have, if either was occuring. The only thing I know for sure is that they have been under a LOT of stress lately. They went to see a doctor today, who sent them home, with a return appointment on Monday, and if there was no improvement, to see a specialist. I'm more than a little worried. Should I be? Thanks in advance, folks.

No, LOL, didn't swallow a golf ball (I would hope they woulda mentioned that little tid-bit). I told them it probably wasn't anything really serious IMHO, because of: the fact that like you said, the Doc sent them home, plus the fact that it appeared so suddenly. Add to that the lack of breathing or swallowing problems, and no mention of it being anywhere near the spine, leads me to think it may just be a really large cyst or something. BUT.....my best friends' father went from just "having a little difficulty swallowing" to dead in less than a month from throat cancer. That's why I'm worrying, I guess. Watching him go was really hard. I hope I'm worrying for no reason.

They are going to need to see an endocrinoligist, pronto.

Sounds like a brachial cleft cyst.
cpermd

If it's not pulsating, I'd guess a salivary gland cyst.  If so, I wouldn't worry too much about it.

Allergic reaction, maybe?  I haven't had any golfball-sized lumps, but I had one that made my lip swell up to about 4x normal size.

Insect bite??  If he's allergic to that bug, maybe?