This is a cyst that I recently had carved out of my head. It started growing about 7 years ago. For most of it’s lifespan it was quite small. Then one day I noticed that, “Holy shit this thing’s pretty big now!”
So I had a dermatologist slice it out of my head. Apparently, as cysts go, these scalp cysts are pretty common. They start with a clogged or damaged hair follicle.
Pretty gnarly, eh? 🙂