Curious how many vets have seen this.

This is curiosity based. I am a vet tech and my dog has had a hygroma that turned into an infected mass several times over the past 3 years. Most vets wouldn't touch it but finally got it removed. Before it was removed and finally fna'd, I noticed calcium like material come out.

I guessed it was calcinosis circumscripta and ended up being right via biopsy. I have vet friends and acquaintances that didn't fully believe me because it's so rare. Until I got the results back.

How rare is this and have you seen it?