How did this fake medical term make it into a peer-review journal?

Spot quiz: Where in the body is the Xander ligament? 

Yes, this is a trick question.

The ‘Xander ligament’ is a term made up by a US graduate student, Alexander 'Xander' Toftness, who produces educational science videos on YouTube. 

And yet the ‘Xander ligament’ is cited in an article in Mayo Clinical Proceedings on neoplastic haematology, called ‘Management of Muscle-Invasive Urothelial Cancer and the Emerging Role of Immunotherapy in Advanced Urothelial Cancer’. 

So what