u/Ginkachuuuuu

This guy just recently started growing these weird tumors. They're only on the tips of two of his arms, and are hard and dry to the touch. The only thing I can find online that's similar is black gall, but I've never heard of that affecting cactus. I've never seen anything like this in my collection before so I'm hoping someone here will have some insight.

I plan to chop both affected arms off for safety, but really hope it's not some weird virus that has spread through the whole plant.