Hi Ein,
My dad went through a similar set of doing tests, getting phone calls with the results, and waiting for appointments with DRs, and then the decision to do more tests. My dad had two spots in his right shoulder area (not common at all for an initial met to appear), and he went all the way from bone/ct, to xray, to mri, to needle biopsy before he got some (agurably) convincing evidence that what was in his shoulder was a benign cyst, and not a met. Up until the needle biopsy (that was pretty much demanded by my mother), all drs were convinced it was a met.
What's more interesting is that two medical oncologists, even with the bone biopsy results, were not 100% convinced that the spots were NOT mets, probably due to the possibility of "micro mets" that Zufus refers to above, as well as my dad's other stats (GS 8, low PSA - which has the possibility of being a more agressive form of PCA).
The treatment options given to my dad with his entire profile were surgery (with the acknowledgement that surgery was probably step 1 of at least 2 treatment plan), or HT + radiation. My dad decided that the best option for him personally was HT + radiation. Well, when he went back to the med onc for his first HT shot, the doctor said that they will watch the spots in his shoulder for 3 to 6 months, and if it doesn't change at all (further evidence that the spots really are NOT mets), that surgery could still maybe an option, as opposed to radiation.
That was somewhat surpirsing, but also encouraging in that he hasn't had to eliminate any options down the road. There is some prelim evidence that neo-adjuvant HT (done before surgery) does help decrease the size of the tumor, so I do understand why the option is at least on the table.
At the end of the day, my dad's experience mirrors the opinions of others who have written above, that with one hot spot, especially when it has a higher probability that it ISN'T a met, your treatment options will likely be similar to those without mets. I think what endded up influencing my dad's decision to go HT vs surgery was thinking that doing something systematic (as opposed to local) gave him the piece of mind that even if there are cancer cells floating around somewhere else in him, he was doing something about it. But again, the dr told him both options had equal chances of effectively treating his case. So at the end of the day, decide what works best for you based on your dr.'s recommendation.