Could one tattoo a person with harlequin ichthyosis, or would the exceptionally fast rate of cell shedding and reproduction prevent the tattoo from taking hold?
No, really, I’m curious. And yes, people with harlequin ichthyosis have survived to adulthood.
I’m sort of wondering why someone with a skin problem like harlequin ithyosis would seek out someone to jab inky-covered needles into them, I mean, isn’t the condition painful enough?
Yes, I think a tattoo would “take” on an HI sufferer as the ink is injected into the dermis, not the epidermis which sheds. After all, regular skin remains tattooed for decades despite cells migrating upwards and shedding, why shouldn’t someone with HI remain tattooed?
Harlequin ichthyosis is incredibly rare; 10 people in the US have it. The oldest known surviving Harlequin patient is a 26 year old woman in the UK. So I don’t think there’s been a lot of research into the area.
Theoretically, it shouldn’t prevent the tattoo from setting, as ichthyosis is a disorder of the keratin in the epidermal layer of the skin, and tattoo ink is placed below that, into the dermis. The dermis isn’t the problem in harlequin ichthyosis; it doesn’t shed.
More common forms of ichthyoses (some of which are so mild that people don’t know they have them, they just believe they have very dry skin) shouldn’t present a tattooing problem. Ichthyosis isn’t made worse by irritation or scarring, and again, since the tattoo ink is below the keratin layer of the skin, the tatt should set just fine.
Obviously, this is a “speak with your doctor” issue for any particular case, though!
This was theoretical, not personal. 
Well, that’s good. Figured I should add it, though, since this thread is likely to come up if anyone googles “Harlequin ichthyosis and tattoos”. 