I have grown these fibers myself, but they are barely visible with the naked eye. The people in clinical medicine, in particular infectious diseases, know about it.
They are just confused about what they are.
I have pictures of similar structures on my website, http://www.ummicrographic.com
in the image section under the "scalp" folder.
These are nowhere near as aggressive as the ones you are showing, but I assume they are similar in the way they develop.
Shroom