Cankers/spontaneous bark explosion?

[dafunk]

Hello all,

Came across this the other day. It is a two stem Norway maple, where on stem is covered in what looks to be many small cankers all over the main stem and branches. Any ideas?

 

[Jason Douglas]

Some look like small burls, some cankers, others a gall. Weird.

 

[Tom Crosthwaite]

Interested to see the answer to this too http://trickytreesolutions.com/