THE SKIN YOU WERE BORN IN
The skin is your body’s outer covering, which protects against heat and light, injury, and infection. Skin regulates body temperature and stores water, fat, and vitamin D. The skin, which weighs about 6 pounds, is the body's largest organ. It is made up of two main layers: the epidermis and the dermis. The outer layer of the skin (epidermis) is mostly made up of flat, scale-like cells called squamous cells. Under the squamous cells are round cells called basal cells. The deepest part of the epidermis also contains melanocytes, cells that produce melanin, which gives the skin its color. The inner layer of skin (dermis) contains blood and lymph vessels, hair follicles, and glands that produce sweat, which helps regulate body temperature, and sebum, an oily substance that helps keep the skin moisturized.
WHAT ARE HYPERPIGMENTATION AND HYPOPIGMENTATION?
Hyper- and hypopigmentation are forms of skin discoloration. The skin does an amazing job protecting us from the ravages of daily life, such as, sun, pollution and other environmental factors. However, when the skin becomes injured or even during the normal aging process, it may darken and start to show uneven brown spots. This is known as hyperpigmentation. Hyperpigmentation is a common, usually harmless condition in which patches of skin become darker in color than the normal surrounding skin. This darkening occurs when an excess of melanin, the brown pigment that produces normal skin color, forms deposits in the skin. Hyperpigmentation can affect the skin color of people of any race.
On the opposite side of the coin, Hypopigmentation is the loss of skin color; it can appear pinkish and lighter in tone than the rest of your skin color. This is caused by the depletion of melanin, related to sun damage and sometimes can occur due skin inflammation or vitiligo.
ABOUT DARK SPOTS
Freckles, sun spots, brown spots, dark spots, age spots or "liver" spots; none of these sound very attractive, but they are all terms that are used to identify a form of hyperpigmentation. They occur due to sun damage, and are referred to by doctors as solar lentigines. These small, darkened patches are usually found on the hands and face or other areas frequently exposed to the sun.
Usually treatment is required to eliminate them and, even then, results are temporary. Take proper precautions in the sun and you’ll keep sun spots from appearing.
Moles, dark spots and growths on the skin are usually harmless — but not always. Anyone who has more than 100 moles is at greater risk for melanoma. The first signs can appear in one or more atypical moles. That's why it's so important to get to know your skin very well and to recognize any changes in the moles on your body. Look for the ABCDEs of melanoma, and if you see one or more, make an appointment with a physician immediately.
- Asymmetric — A brown spot will generally remain the same shape and size, whereas a cancerous spot transforms and changes shape and size. Cancerous spots’ shapes tend to be distorted and become irregular in color and size. If you draw an imaginary line through the mole and the two halves do not match, see your physician. The moment your spot starts changing in any of these regards, it’s time to visit the doctor.
- Border — The borders of an early melanoma tend to be uneven. The edges may be scalloped or notched.
- Color — Brown spots will be just that — a brownish color, like a freckle or mole. Melanoma can also be brown, but can also have pigments of white, red, and pink.
- Diameter — Melanomas are usually larger in diameter than the size of a pencil eraser (1/4 or 6mm), but may sometimes be smaller when first detected.
- Evolving — Any change in size, shape, color, elevation, or any new symptom such as bleeding, itching or crusting points to danger.
- Always keep an eye on any brown spots to make sure they aren’t cancerous. Even though a brown spot and melanoma can look similar, these are just some of the visual differences to look out for. Just remember, if you’re at all uncertain, visit your dermatologist. It’s better to be safe!
WHAT IS PHOTOSENSITIVITY?
Some medical conditions, skin treatments, and medications cause skin to become abnormally sensitive to the sun; this increased sensitivity is known as photosensitivity. Those with photosensitive usually experience a skin rash caused by UVA and UVB rays, on their face, arms, hands, and chest.
There are numerous conditions, medications, and even sunscreens that can cause photosensitivity.
Skin conditions that can cause photosensitivity:
Medical conditions that can cause photosensitivity:
- Crohn’s disease
- Multiple Sclerosis
- Lyme disease
- Bloom Syndrome
- Xeroderma pigmentosum
- Sjogren’s Syndrome
- Dravet Syndrome
- Photodynamic therapy for skin cancer
Medications and drugs that can cause photosensitivity:
- St. John’s Wort
- Antibiotics (Tetracycline, Cipro, Levaquin, Oracea, Atridox, Bactrim, Septra, Phisohex)
- Antihistamines (Benadryl)
- Acne medications (Accutane, Soriatane)
- Psychiatric drugs (Thorazine, Norpramin, Tofranil)
- Retinoids (Retin-A, Isotretinoin, Acitretin)
- Pain killers and anti-inflammatories (Celebrex, Ibuprofen, Naprelan, Aleve, Anaprox, Feldene)
- Coal tar
- Oral contraceptives
- Diabetic drugs (Diabinese, Micronase, DiaBeta, Glynase)
Ingredients in sunscreens that can cause photosensitivity:
- Para-aminobenzoic acid (PABA)
Cancer chemotherapy drugs that can cause photosensitivity:
- 5-fluorouracil (Efudex, Carac, Fluoroplex)
- Vinblastine (Velban, Velsar)
- Dacarbazine (DTIC-Dome)
 — http://www.medterms.com/script/main/art.asp?articlekey=7901
 — http://www.nlm.nih.gov/medlineplus/ency/article/003242.htm
 — http://www.aocd.org/skin/dermatologic_diseases/hyperpigmentation.html
 — http://americancancerfund.org/basic-cancer-info/basic-info/skin