What Causes Painful Boil On Skin?

hi, my dad has had this stuff on just his hands for 7 years and no one can figure out what it is we have been to 3 dermatologist 3 doctors and surgeons and has had 4 biopsys but it starts out looking like a zit or a boil and it builds into a callous. It hurts him so bad to where he cant leave them alone. and underneather the surface of the matter are hundreds of these white hair lookin to as big as a rice grain. We dont know what they are but the big round ones seems like it has its own membrane ( when you squeeze them in the tweezers they pop). The smaller to medium size he has to wait and let them dry out for him to grab because they are so heavily rooted in the skin? have you heard of anything like that or have any suggestions?