Skin Pigmentation

Melanin

Melanocytes are cellsThe basic structural and functional units of life. in the stratum basaleThe deepest layer of the epidermis, where new skin cells are formed. that make melaninA brown-black pigment made by melanocytes in the stratum basal and given to keratinocytes as melanos, a brown-black pigment.  These melanocytesCells in the stratum basale that produce melanin, the pigment responsible for skin color. are always making melanin, but UV radiation provokes them to accelerate their production of melanin.  The excess melanin accumulates on the apical surface of the nucleusThe control center of the cell that contains DNA and directs cellular activities. of melanocyte.  This is the surface that is facing the sun and potentially being exposed to lots of UV radiation.  The melanin absorbs that UV radiation before it reaches the nucleus of the melanocytes. It protects the DNA from mutationA change in DNA sequence that can affect gene function., which could generate a potentially cancerous change.  A cancerous mutation in a melanocyte will create melanomaA dangerous form of skin cancer that originates in melanocytes., one of the most aggressive cancers in skinThe body’s largest organ, providing protection and regulation.. 

The vesicles of melanin don’t stay just inside the melanocyte.  Melanocytes transfer their melanin rich vesicles to the other cells in the stratum basale and the surrounding keratinocytesThe most abundant cells in the epidermis, responsible for producing keratin..  As the keratinocytes move superficially, the melanin vesicles move with them and break down when the cells die.  The other cells in the stratum basale benefit from the UV-absorbing melanin. Stem cells constantly create keratinocytes, and melanin accumulates between their nucleiClusters of neurons in the CNS responsible for processing information. and the incoming UV. 

Skin Cancer

Skin cancers are so named for the cells they affect.  The more aggressive a cancer, the less common it is.  The opposite is also true – the less aggressive the cancer is the more frequently it will appear.  The bottom pictures here are all of different types of melanoma.  The top row shows you some of the more common types of cancer. I have to admit that I’ve never heard of Merkel Cell carcinoma.  A Merkel cell is an encapsulated ending of a sensory nerve. It senses touch. 

A basal cell carcinomaThe most common type of skin cancer, arising from cells in the stratum basale is cancer of any cell other than a melanocyte in the stratum basale.  These are usually the stem cells that make keratinocytes at a moderated rate. They are now doing too much mitosis. They are making too many cells.  A squamous cell carcinomaA type of skin cancer arising from the stratum spinosum. is cancer, or too much division of a keratinocyte.  Keratinocytes are exposed to all of the types of UV rays.  If the DNA, which suppresses mitosis in a keratinocyte, mutates and releases that suppression, the keratinocyte will start to divide. It will make a tumor.

Think about how much skin you’d have to scoop out to get each of these types of cancer.  How deepAway from the surface of the body. do you have to go?  Mohs surgery answers just that question.  It is also a surgery that can keep you at the hospital all day.  They take some cells, fix and stain them, then look at them under the microscope.  3 hours later they do the same, 3 hours after that the same.  And they keep doing that until they get a sample with no cancerous cells.

Melanomas

How do you know if you have skin cancerAbnormal growth of skin cells, often due to UV exposure.?  Have a dermatologist tell you.  There are some things you can look for, which are listed here.  All of these pictures here are melanomas.  Side note – if a lesion on your skin meets all these criteria, run, don’t walk to a dermatologist.  Melanomas always meet all criteria.  The issue is not that your mole is asymmetrical. I have asymmetrical molesDark pigmented skin growths caused by clusters of melanocytes.. What is important is if that asymmetry has changed.  Did the border of your mole go from smooth to wavy, did the color change, is it getting bigger?  If it changes over time, have a professional assess it. 

Melanoma Stages

I found this picture on the website that I use for our pictures.  This is a great example of cancer in general.  A tumor results from a cell that takes off the brakes on its mitosis.  The additional cells grow until they span the full layer of the epidermisThe outermost layer of the skin, made of stratified squamous epithelium..  As the tumor grows, some pieces start to break off.  These pieces deposit into the lymph nodes and other areas of skin.  True metastasis occurs when pieces start appearing in distantly located tissues, usually the lungs and spinal cordThe central nervous system structure that relays signals between the brain and body..

Other Pigments

Yes, there are other pigments than melanin.  Carotene, of course, gives a more orangey-yellowish appearance and is present in Asian gene pools as well as Eskimo-lineages.  Hemoglobin is the pigment in your blood. It gives a ruby red color when oxygen is attached. It turns dark red purplish when oxygen is unattached.  Bilirubin is the yellow pigment in bileA digestive fluid produced by the liver and stored in the gallbladder; it helps emulsify fats for di. 

Pigments Make you Look Funny

No matter what pigments you make and in what abundance, there are skin conditions that result from diseases or emotions. 

Cyanosis results from that dark red purplish color on unoxygenated hemoglobinThe oxygen-carrying protein in red blood cells that gives blood its red color..  Cyanosis can be found with anemias and poor circulation. It also occurs with emphysemaA lung disease in which alveoli are damaged, reducing surface area for gas exchange and causing shor and other diseases. These affect your ability to oxygenate your blood.

Erythema is blushing.  This can also be the result of thermoregulation when your body is trying to cool you down.  Hot, red, blood is brought to the surface of the skin to allow the heat to dissipate.

Pallor and cyanosisA bluish skin discoloration due to inadequate oxygen in the blood. can be confused because they can be caused by similar conditions relating to oxygenation.  Pallor and goosebumps go together often when someone becomes frightened. 

Jaundice occurs from an overabundance of file or a pigment called bilirubinA yellow pigment produced from the breakdown of hemoglobin, excess amounts cause jaundice.. This yellowy pigment can be easily seen in the whites of the eyes. It starts to accumulate in systemic tissues. Jaundice can come from a few problems, most relating back to the liverA large organ that produces bile, detoxifies blood, and stores nutrients. which is the manufacturer of bile. Issues with the gallbladderA small organ beneath the liver that stores and releases bile into the small intestine. and lipid digestion in general can lead to jaundiceA yellowish skin discoloration caused by excess bilirubin, often due to liver dysfunction..

Bronzing is a very different condition. It can often be confused with jaundice because of the yellowish color. Bronzing actually makes people appear shiny. This is the result of a disease called Addison’s disease. This disease causes over-functioning of the adrenal glandPaired endocrine glands above the kidneys producing stress-related hormones.. It pumps out cortisolA glucocorticoid involved in stress response, metabolism, and immune regulation. to the systemic tissues.

Carotenosis is quite rare. It is very easily seen in people who don’t have a lot of melanin in their epidermis. It is often associated with newborn babies and first-time parents. Feeding your infant an abundance of carrot-based baby food can actually result in carotenosis. If the child has skin type with very little melanin, the carotenosis is visible in the subpapillary plexusA network of blood capillaries that vascularize the papillary layer of the dermis of skin. Loops ext. It is also visible in the cutaneous plexusA network of blood capillaries that vascularizes the hypodermis/dermis border of skin. through all the layers of the melanin-deficient epidermis.