The changes to the skin on my left breast are definitely morphea, a type of scleroderma. The biopsy sample was good: it was 0.5cm by 0.4cm and went down into the fatty tissue below the derma, or skin layer. There were areas of sclerosis in the derma that went all the way down into the fat so the changes are quite extensive.
No one really knows what causes morphea. It's thought to be an autoimmune disease and it shows up as a long-term side effect of radiation. The cases I've seen have shown up much sooner than 11 years after radiation like mine did. I can imagine a scenario where my immune system was wonky because of the cancer and sarcoidosis and the denosumab just added enough strain to my already-weird system for the morphea to take hold.
There aren't really any treatments for morphea; pretty much everything is done off-label on an experimental basis because nothing really works. The best treatment is a systemic one - I think it's cyclophosphamide, a type of chemotherapy, and it works by suppressing the immune system - but my system is fragile enough that we don't want to introduce a new systemic treatment until or unless we have to do it.
There's another topical treatment I could do but I'd need to see him every two weeks and there's no guarantee it will work. I don't think he thinks it's worth trying, partly because I'd have to travel so far. If I lived in Oakville, things would be different. Before I make a decision one way or another on whether to try this treatment, he wants me to talk to my oncologist and family doctor to get their thoughts. So we'll see. I'm not convinced that it's worth trying to get rid of it, especially since it's not life-threatening or anything. Besides, if chemotherapy clears this thing up, it'll get cleared up when I'm the "lucky" recipient of chemotherapy for the cancer - whenever that happens (which hopefully won't be for quite some time yet).
Oh, and the dermatologist thinks that the incision is healing up quite well. He told me that sometimes infection will take hold and be tough to get rid of so if there are any signs that the infection is returning, I need to get to the ER right away. I'll definitely do that: I don't want to wind up in the hospital with IV antibiotics.