Global Period

Dr saw a patient who is still in the 90 day global for a thyroidectomy. The patient has developed a keloid at the incision site(which dr notes that this is common for the patient) and he does a Kenalog injection. I am stuck on which modifier to use. I was thinking a 78 but dr notes that this is a common problem for the patient in the past. What would you use in this situation? Or would you not bill the injection since the patient is within the global and the problem is related to the original procedure?

re: Global Period

I would lean more towards 78, just because it's "common" does not mean it's inclusive to the original procedure.
My opinion.