Metalosis Maligna is a fake disease invented by award-winning Dutch filmmaker Floris Kaayk.
According to the mockumentary, Metalosis Maligna occurs when a metal implant has a bad interaction with human body tissues, causing the metal to grow tendrils that eventually puncture the skin from within and destroy it.
I was skimming through the video at first not knowing it was a mockumentary and landed on the part of the man in bed. I nearly died.
Here’s an alternative link to watch it on vimeo, in higher resolution, from the creator’s channel.