Partial Excision

“I have a patient with a possible 1st proximal phalanx cyst vs infection that I plan to do an exploratory procedure and collect some bone cultures / swabs on. MRI was inconclusive. If I get in there and the bone appears necrotic/infected, I will have on the consent form to allow for a PIPJ arthroplasty. So, we'll get prior auth for all these procedures prior to surgery. But, for the initial planned procedure, how would this be coded?”