In the world of crazy skin ailments, Blaschko’s Lines are certainly interesting. Discovered by Alfred Blaschko in 1901, this condition is manifested by a V-shaped pattern of lesions over the back, with S-shaped swirls all over the front side of the trunk. People can have the tendency toward this condition without it ever manifesting, until something like a pigment disorder or another problem manifests and BAM! Stripey skin.
Funny enough, the condition is common in people who have Chimera. The lines reportedly follow the “migration of embyronic cells” and can also be found in animals.
To reiterate, the disease is invisible, until the sufferer develops a skin condition that causes the patterns to manifest. Some of the skin conditions that can make the disease manifest are focal dermal hyperplasia, CHILD syndrome, MIDAS syndrome, sebaceous naevus, McCune-Albright syndrome, Lichen striatus, linear morphoea, and a bunch of other skin disorders you may have never heard of.
Blaschko’s Lines are often talked about in relation to mosaicism, which is a condition similar to and related to chimerism. In mosaicism, the person or animal has two distinct genetic populations of skin cells that live side by side with one another. Blaschko’s Lines are the Type 1a and 1b forms of cutaneous mosaicism. Not all sufferers of cutaneous mosaicism have Blaschko’s Lines, and not all people who have Blaschko’s lines also have cutaneous mosaicism.
The general thought is that all skin has these stripes, but the conditions we talk about above are the ones who bring the stripes to light.