Argentine boa missing scales

Just as a background, got this Argie about two months ago. He had a couple of issues and was way underweight. He is about 6.5 ft and was just over 7 lbs. when I got him. He is healthy and a great feeder and is over 9 lbs. now. He was a little snippy at first but he's a teddy bear now and tolerates inspection and treatment better that any other snake I have. Now to my question; in two areas on his skin he has just skin no scales. There is no scar just missing scales. One area is irregular and totals and area the size of a quarter, the other area is the size of a dime or less. He was quite dull and in the final phase of pre-shed when I got him so given his dark color I could have missed this. He had a good shed but I still didn't see these areas until last week after I bathed him. Will these area remain scale free? Will they regrow as he sheds in the future. This could be a case of someone trying to help him shed in the past or he may have gotten a scrape while in my care which is virtually impossible in this case. Just want to know what to expect regarding these two areas. All input is appreciated.

hmm I wonder if the boa was ever injected with baytril? I know that can lead to a scaring type situation or white patches without scales. Or it could be an older injury? It's hard to say without seeing it and without knowing what it's been through. Scales may or may not grow back.