Is this a well-known skin condition? (If you enjoy fried chicken DO NOT click)
http://blog.wfmu.org/freeform/2007/03/missionary_enco.html
They briefly mention the name of the condition but I can only find a very short description using google. I’m sorry if this has been posted before, but I would really like to know more about this. 
My medical dictionary is listing Lewandowsky-Lutz disease, the disease your link says this man was diagnosed with, as being another name for epidermaldysplasia verruciformis.
Epidermaldysplasia verruciformis, it goes on, is: “the widespread and persistent, sometimes for decades, dissemination of verruca plana associated with a tendency to malignant degeneration. It typically begins early in childhood with the develpment of flat-topped papules, varying in color from pink to flesh, to grey or brown, which increase in number and coalesce to form large plaques, especially on the knees, elbows, and trunk. Familial ocurrance, parental consanguinity, and menatl retardation are often associated with this disorder.” *Dorland’s medical dictionary, Saunder 2003 *
IANAPatholgist, but what he has doesn’t look like coalesing plaques to me (unless they are the buffest plaques ever). It looks like cutaneous horn. From what I understand, cutaneous horn can be an exuberant response by the skin to injury. The one case I have seen was a goat who suffered 3rd degree burns in a fire, and the owners kept it going for several months with home care and silver cream.
My WAG differential list with absolutely no diagnostics:
traumatic damage the skin the hands and feet: virus, toxin, or sunlight
Genetics: allergy, or an inability of the skin to respond properly to any of the toxins listed above.
Short answer: I don’t think this is common. If you have a friend who is in the medical field, ask them if they know a dermatologist to pass the pics along to. Most folks in the medical field love gruesome disease pics.