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A 32-year-old Caucasian woman comes to her primary care provider's office because of non-pruritic skin changes for the past year. Her past medical history is significant for type 1 diabetes mellitus. She states that there have been small patches of depigmentation of the back of her hands and arms for as long as she could remember. She also reports of recent constipation and fatigue. She states that she has felt colder than usual. A lipid panel done 2 years ago showed normal laboratory values. Physical examination shows a well-appearing female with widespread macules and patches on her hands, arms, and legs. These lesions are amelanotic, symmetrical, and measure up to 6 cm in diameter.
Content Reviewers:Rishi Desai, MD, MPH
Vitiligo, likely meaning blemish, is a non-contagious skin condition that is defined by patches of discoloration, or depigmentation.
Though vitiligo can affect any race or ethnicity, it tends to be most noticeable in people with darker skin, like Canadian fashion model Winnie Harlow.
Given the effect on a person’s appearance, pigment loss can really impact a person’s quality of life.
The hypodermis is made of fat and connective tissue that anchors the skin to the underlying muscle.
Just above is the dermis, which contains hair follicles, nerves and blood vessels.
And just above, the outermost layer of skin, is the epidermis.
The epidermis itself has multiple cell layers that are mostly keratinocytes - which are named for the keratin protein that they’re filled with.
Keratin is a strong, fibrous protein that allows keratinocytes to protect themselves from getting destroyed when you rub your hands through the sand at the beach.
Keratinocytes start their life at the deepest layer of the epidermis called the stratum basale, or basal layer, which is made of a single layer of small, cuboidal to low columnar stem cells that continually divide and produce new keratinocytes that continue to mature as they migrate up through the epidermal layers.
But the stratum basale also contains another group of cells - melanocytes, which secrete a protein pigment, or coloring substance, called melanin.
Melanin is actually a broad term that constitutes several types of melanin found in people of differing skin color.
When keratinocytes are exposed to the sun, they send a chemical signal to the melanocytes, which stimulates the melanocytes into making more melanin.
The melanocytes move the melanin into small sacs called melanosomes, and these get taken up by newly formed keratinocytes, which will later metabolize the melanin as they migrate into higher layers of the epidermis.
Melanocytes can also be found in the dermis, at the base of the hair follicle, and in the eye where they help color hair and the iris.
In vitiligo, there’s a loss of melanocytes or an absence of their function. Histologically, a less melanin in the epidermis results in white depigmented patches. These patches are classified by type.
There’s non-segmental vitiligo which is the more common type that affects any age group, and it occurs at various locations that are mirrored on both sides of the body.
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