Bf has testicular cancer. could ultra scan be wrong and he is fine? or naive, wishfull thinking on my part?

Why do you ask?: If there's a testicular mass, the diagnosis of cancer is not certain until the pathologist has made the call. Thankfully, the vast majority of testicular cancers are curable nowadays. Best wishes to you and your boyfriend.

Well: ...It would be nice if he didn't but if the us is convincing, they need to proceed as if he has it. Do remember that testicular cancer is one of the most curable cancers we see, even if spread, so keep your spirits up and tell him to fight well. Best to both.