If it was a hematoma, it may just come back. If it does, you should have it evaluated by your Vet to try to determine the cause. They often have to be aspirated or surgically removed. In the mean time, do try to keep it clean.
Hi,these can look just awful,I had a Rottie who had one,
though it was a small hole after it ruptured I did take her
into our vet as it looked deep to me.
He did clean it and put two small sutures in it so it would
close and heal without infection,Zena was put on oral
antibiotics after her ear flap was cleaned by our vet,it all
turned out great and it was not visible after it healed.
Jan