Lipstick Tang Cyst ????

HI,
Introduced this lipstick tang into tank about 4 months ago. Was a small fish and our hippo tang took a dislike to him straight away. Within the first few days he stabbed (cut) him with his spike.
Well after a few days the feuding was over.
But the cut has now developed into a cyst type of wound. (looks like a whitehead pimple that needs squeezing)
Does anyone know if this will disappear or may become a problem ?
He eats,swims and play normally ?
I just thought after 4 months it may have gotten better ?

If the tang is swimming and eating normal, give him some time to heal. Just keep feeding seaweed.

I have almost no experience with tangs, but I agree with Mario give it time and keep the greens up.