Port Wine Stain; Most often occurring on the head and face, these marks are the result of malformed blood vessels. They are present at birth and last the persons whole life, growing with them as time goes on; they are usually harmless to the persons health.
Vitiligo; Caused by the death or loss of function of pigment-producing cells in the skin, vitiligo results in the gradual loss of pigmentation of the skin over time. There are many types of vitiligo patterns, but patches usually occur symmetrically and on joints and points of impact, like the hands, elbows, and face. Vitiligo can occur on people of any race.
Freckles; Most commonly found in fair-skinned people, freckles are caused by over-active pigment-producing cells, which leads to small areas of over pigmentation. Exposure to sunlight makes the pigment cells work even harder, so freckles can get darker when exposed to sunlight.
Albinism; True albinism is the result of a genetic disorder that causes the cells of the body to be unable to produce melanin (skin pigment). In many cases, albinism is linked to various eye problems, but otherwise has no ill effects (other than susceptibility to UV radiation from the sun!). In small animals, albinism causes their eyes to be red due to visibility of blood vessels; in humans, the eyes don’t always lack colour, but can appear pale blue, red, or even purple!
Mongolian Spots; Named as such because they are most common in people of Asian, Oceanic, and Native American descent, these spots are caused by pigment-producing cells being trapped deeper than normal below the skin. They usually manifest on the lower half of the body, and usually don’t last past childhood. They really do appear blue, though!!
an update of this old post, which is almost two years old! I’ve improved a lot, and hopefully this new version can start making the rounds, instead of the old version. This one is much better, isn’t it?