Terrib - Of course you know your husband better than anyone here and can probably judge his reactions, so these are just my thoughts for whatever they are worth:

If you DO tell him, I would start with all the positives, i.e. it's just something the doctors want to check, it hasn't grown any so they just want to be sure with a biopsy. It's not cancer until a biopsy says it is. And you can leave it up to him whether he wants others to know. That way he still has some measure of control. With Christmas so close, you can keep him busy until biopsy time.

If you do NOT tell him, you may risk his not believing you whenever anything else comes up in the future. When my son was in treatment, I always told him the truth, but when Rads ended and we were just going to Dr. appointments, he reached a point where he did not want me to go with him. I don't know if he had doubts about my telling him everything or he just wanted to exercise his prerogatives as an adult - which he had a perfect right to do.

Because you and your husband know each other so well, you may also be communicating by non-verbal means. A certain look or expression on your face or other body language may give away what you are feeling. (Unless you are a very good actress).

If it were me, I would want to know the truth. With the truth you are better able to fight the fight and do what you have to do to survive.