My husband has about more or less 1.5 inch lump in his back between the shoulder blades. movable, painless didn't change in size. what could it be?

Some thoughts...: A movable, painless lump on the back might be a sabaceous cyst (not much trouble unless infected), or a benign fatty growth called a lipoma. But the fact is, it's a lump. Have your husband's doctor look at this. One surgeon i know says, "the best place for a lump is in a specimen bottle." of course, that's not always the case - but have his doctor evaluate him to be sure.