Should I be concerned?

BPH Can cause an enlarged prostate, which then can cause a high PSA. The thing is the MRI did find Three possible lesions with a PIRADS 4 score. They do not guarantee that there is prostate cancer, but they do make it likely.

If you could get a PSE test, it would be able to tell you whether or not there was prostate cancer in your system, If it says no, then you don’t need a biopsy. It is 94% accurate. Just another option, Not sure if you have that available, but it is FDA approved.

I agree with @jeffmarc. The PSE test is a blood test that looks at 5 biomarkers and the results say either you are likely to have prostate cancer or unlikely to have prostate cancer. Here is a link to the Oxford Biodynamics web site that talks about this test.
https://www.94percent.com/

Thanks for the feedback

Thanks for the feedback, I researched the PSE test it’s something I definitely would do , however after looking into it not many Drs in my area are advocates.

Yes, PSE is approved for screening, but it hasn't become normal standard of care yet. The medical community is probably waiting for more confirmation from independent studies (especially following patients long term) before deciding whether to adopt it.

With a 12.9 PSA, you should be concerned, but…with a great surgeon having done a couple thousand DaVinci Robotic-Assisted RP surgeries, in a well known, highly regarded medical center of 400 beds or greater, you should be fine.
The key is finding an outstanding urologist, and having a bit of luck.
You will get your Gleason score from the biopsy, but it is only the cursory, “tip of the iceberg” information. It doesn’t really tell you anything, so make sure your urologist orders the “Decipher test.” That is a test for 23 prostate cancer-specific genes and mutations that offer a risk assessment score for how bad your cancer is, and offers an estimate of your longevity. You won’t know your fate until you get your surgical pathology report that tells you “everything.”
I had a borderline Gleason score of 3+4=7 with only 10% of cells being the grade “4”. I was mostly “3” level cells with a tumor that took up 30-40% of my prostate per the 12 core samples taken (three negative, three 3+3=6, and six as 3+4=7 with only 6-10% “4” cells). My overly confident urologist changed his tune when my surgical pathology report yielded EPE, surgical margins, left seminal vesicle invasion, and Cribriform glands, all pretty ominous stuff. My urologist then said: “Gee…it seems your cancer was a fairly aggressive cancer…we need to talk about radiation next visit”. What?!?!
It all starts with a VERY experienced urologist. Travel to the next town or wherever there is a ~400 bed hospital, hopefully a teaching institution hospital, to find the highest level of competence and experience. Make sure they have the DaVinci Robotic RP machine. Your life depends on it.

Sorry to report - we had overly confident surgeon (7000 + surgeries) at UC hospital.
We were told "not urgent" but should start thinking about a treatment, like in next year or so, even though biopsy already showed cribriform and IDC. We wanted treatment immediately, but we were told "no rush". WE still made app. for surgery and ended up with "all that bad stuff" in a pathology report. I can only imagine what would be in a year or if we went with "focal treatment" that was mentioned as an option (?!)
So - bottom line, yes , your life depends on it and DO NOT WAIT. Start a treatment as soon as possible.