I am so sorry you had to wait days for a reply. If you can easily do it, why not upload the photo to your profile page? That would be the best way for others to see it here.
But, even if we do see it, no-one can be 100% certain what a lump is made of.
It may be a harmless sebacious cyst, or trauma, or a tiny fatty lump called a "lipoma"....or it may be something more serious, so it's not wise to rely on someone's guess from a picture.
The only sensible thing you can do is take your dog to the vet and get this lump checked.
Breast (mammary) cancer in male dogs is pretty rare, though common in older females who were not spayed before their first "season".
I personally, have my doubts that it would be that kind of cancer, but it could be something else that needs quick attention, so please take him to a vet.
However even if it's the worst-case scenario (rare as I said, among male dogs), a lumpectomy with good margins will often get rid of the problem, and if it is further distributed in breast tissue, then a full or half -mammary strip will be the ultimate cure in a large percentage of cases, so long as there is no spread.