Epidermodysplasia verruciformis (EV, also called Lewandowsky-Lutz dysplasia), colloquially known as tree man illness is an extremely rare autosomal recessive genetic hereditary skin disorder associated with a high risk of carcinoma of the skin. I think this would be a very cool/creepy mutation for Lioden. It would occur on the lions' paws. It wouldn't be lethal. The cause of the condition is an inactivating PH mutation in either the EVER1 or EVER2 genes, which are located adjacent to one another on chromosome 17. Clinical diagnostic features are lifelong eruptions of pityriasis versicolor-like macules, flat wart-like papules, and development of cutaneous carcinomas. I haven't found any photographs or records of this in non-human animals. However, if it occurs in humans, something very similar can surely occur in other animals. I mean, felines have 90% of homologous genes with humans. So, we aren't all that different, are we? No curative treatment against EV has been found yet. In March 2007, a Romanian man named Ion Toader was diagnosed with this condition. In November 2007, a video of a 34-year-old Indonesian man named Dede Koswara with a similar disease appeared on the Internet. I've found several cases in humans, but it hasn't appeared in non-humans, as far as I know (crazy shit happens in the wild so we never know). All mammals have the same basic skin structure. In January 2016, a 25-year-old patient named Abul Bajandar from Khulna, Bangladesh was admitted in Dhaka Medical College and Hospital and was diagnosed with this condition. A character with epidermodysplasia verruciformis was profiled on season five, episode 20 of Nip/Tuck in 2009. I don't know if anybody has seen this show, but it was a pretty cool episode. It's how I found out about the disease! I'm going to post one semi-graphic picture (depends on how squeamish you are).