i have had a set recently with the same symptom. started on one band, then did the whole screen as what youve shown. i of course immediately jumped to panel failure. however....
after troubleshooting the entire set (tcon tests, panel tests) i found that i could not reproduce the problem on screen unless the main board was plugged in.
what this meant to me was that if it was a panel issue, the lines and defects of any extreme would be present without the tcon or main board plugged in.
i ordered a replacement mainboard and the set worked just fine after.
this may be the case for your as well. it was a 50/50 chance when i replaced the board. it worked in my favor this time. if this doesnt work for you, it is definitely the panel.