I did end up adding one colour for his skin-tone because I wanted him to look like a normal human in his "normal mode". He has two modes "attack/virus mode" and a "normal/dormant mode".
When in his normal mode he looks like a normal human, the large hands are hidden and his skin has no marks.
In his attack mode his coat transforms into large hands which can transform at will and his skin gets covered with blue speckles.