SKIN

SKIN - The external covering of the body; the outermost layer is called epidermis, the next layer is called the dermis, and the lowest layer is the subcutaneous tissue.

• Protects the body from microbes and Ultraviolket light
• Regulation of temperature (sweat glands cool off the body by secreting fluid by the sudoriferous glands) perspiration
• Lubrication (Sebaceous glands are  subcutaneous glands, usually connected with hair follicles. They secrete an oily semifluid matter, composed in great part of fat, which softens and lubricates the hair and skin.)
• Excretion of toxins
• Produces Vitamin D (need UV light from the Sun)
• Sense the outside world (nerve endings)
• Skin is not thick on all parts of the body (eyelids)

Damage to Skin :

Damage caused by UV light:

Sunburn - If you are in the  sun too long, you may get red in a few hours. A bad reaction includes tenderness, pain, swelling, and blistering which is cause from UV light.

Tanning - A tan is a sign of skin damage. A tan may  protect against sunburn, but in reality it is a form of sun damage  and will not prevent further sun damage.  Your skin  "remembers" all damage, and with every burn, the skin  becomes more damaged.

Damage caused by Ionizing Radiation:

• Ionizing radiation causes reddening of the skin (erythema) and/or loss of hair
• Radiation burns are possible but with advance treatment methods not as much today as in the past

Melanin - protects the skin against sun damage, and its rate of production determines skin color—the more melanin produced in the skin, the darker the skin appears. Exposure to the sun causes the melanocytes to increase melanin production in an effort to shield the skin from damaging ultraviolet rays; the resulting effect is a suntan. Freckles, birthmarks, and age spots are also caused by patches of melanin within the skin.

Layers of the Skin:

Epidermis: extremely thin top layer of skin

• It is made up of four to five layers:
• 3-4 dead layers on top of the stratum basalis (basement layer) which is alive

Stratum basalis – basement layer

• Produces cells
• Layer is alive while top 3-4 layers are dead (keratinized)
• Produces melanocytes which produce melanin (we all have the same amount)
• Basal cell carcinomas – too many cells are produced
• capable of producing keratinocytes (prevents toxic substances from entering the body / make up 90% of the epidermal cells in the skin)
• contains Merkel Cells in areas with no hair(function in the sensation of touch)

Dermis: the thickest of the three layers of the skin. It’s also home to most of the skin’s structures, including sweat and oil glands (which secrete substances through openings in the skin called pores), hair follicles, nerve endings, and blood and lymph ves­sels. But the main components of the dermis are collagen and elastin. (connective tissue layer)

• Collagen -  is a tough, insoluble protein found throughout the body in the connective tissues that hold muscles and organs in place. In the skin, collagen supports the epidermis
• Elastin - a similar protein, keeps the skin flexible. This is the substance that allows the skin to spring back into place when stretched

Subcutaneous Layer (hypodermis) - Subcutaneous tissue acts both as an insu­lator, conserving body heat, and as a shock absorber, protecting in­ternal organs from injury. The blood vessels, nerves, lymph vessels, and hair follicles also cross through this layer.

• Attaches skin to the rest of the body
• Muscular layer
• avascular layer

Burns by Degree :

1. Epidermis
2. Dermis
3. Subcutaneous

SKIN CANCERS:

On the rise in the United States (ex. Arizona)

Types of skin cancer : Basal Cell Carcinoma, Squamous Cell Carcinoma, and Melanoma’s

SKIN CANCER NONMELANOMASD AND MELANOMAS

Cancers of the skin are the most common type of malignancy of all cancers

• 50% of people who live to the age 65 will develop at least one skin cancer during their lifetime

The Incidence of skin cancers and melanomas is rising every year

• annual increase in malignant melanoma is 7% per year (the most rapidly increasing rate for any cancer in the United States)
• basal cell and squamous cell carcinomas have increased 65% since 1983

A few theories on why there is such a great rise in theses cancers:

1. the healthy tan is fashionable
2. clothing trends have changed allowing more skin to be exposed
3. depletion of the ozone layer

Although incidence rates have risen, death rates for these cancers have stayed the same over the last 6 years

• Melanomas have increased a little bit
• Nonmelanomas have actually decreased

Melanomas are more lethal than nonmelanomas

• About 7500 people die each year from melanomas

Incidence and Geographic Location:

• People who live close to the equator have a higher chance of developing

Incidence and Skin Type:

• People with fair complexions are 10 times more likely to develop skin cancer
• Albinos, people with xeroderma pigmentosa, light colored eyes and people with freckles are most susceptible
• People with darker skin have higher numbers of melanin (not melanocytes!!!) which is a protective substance against UV rays

Multiplicity:

• Prior skln cancer occurances in an individual increases the odds that a second primary will develop
• These other areas may have been exposed to the same carcinogen
• Weak immune system

Gender:

• Males have a higher rate than females for melanomas
• For nonmelanomas the ration is 3:1 favoring males in developing the skin cancer
• For melanomas males are a little higher than females in ratio

Major cause of All skin cancers is exposure to UV LIGHT

NONMELANOMAS :

Basal Cell Carcinoma :  Basal cell carcinoma is the most common form of skin cancer, affecting 800,000 Americans each year (most prevelant form of all cancers)

• Slow growing
• arise in the basal cells, which are at the bottom of the epidermisin the stratum basal(outer skin layer)
• Chronic exposure to sunlight is the cause of almost all basal cell carcinomas, which occur most frequently on exposed parts of the body -- the face, ears, neck, scalp, shoulders, and back
• Anyone with a history of frequent sun exposure can develop basal cell carcinoma, often referred to as BCC. But people who have fair skin, light hair, and blue, green, or gray eyes are at highest risk.
• 80% occur on the head and neck
• appear as smooth, red, milky lumps
• symptoms are sores that wont go away , itchy patches, warts that bleed
  • Rodent Ulcers – burrow under the skin surface but do not invade vessels or nodes
• Metastisis are rare

Squamous Cell Carcinoma :  Squamous cell carcinoma, the second most common skin cancer after basal cell carcinoma, afflicts more than 200,000 Americans each year

• It arises keratinocytes in the epidermis and resembles the squamous cells that comprise most of the upper layers of skin
• Chronic exposure to sunlight causes most cases of squamous cell carcinoma.
  • also associated with some types of infections, immunosuppresion, chronic inflammatory conditions, and smoking (as in SCC of the Lip)
  • often arise from precursor lesions on the skin
• may occur on all areas of the body including the mucous membranes, but are most common in areas exposed to the sun
  • most common on head, face, arms, hands
• usually remain confined to the epidermis for some time, they eventually penetrate the underlying tissues if not treated.
• appear as scaly, crusty. elevated lesions
•  small percentage of cases, they spread (metastasize) to distant tissues and organs. 85% of the time to the lymph(also lung, bone)

Treatment Options for BCC and SCC:

Excisional Biopsy – removal of whole tumor with surrounding margin

• if the biopsy comes back clear all around then the biopsy was also the treatment

Moh’s Procedure – removal of the whole tumor, while the patient is still on the table the tumor is sent to pathology.  Pathology then decides if the sample is clear but if it is not then the surgeon goes back and removes more.  (Work in a clock like fashion)  This is done until the removal is all clear with enough margin

• good for small lesion
• no guessing on margins / when the Surgeon reaches the margin then the procedure is done
• has not replaced conventional surgery due to cost

Laser Removal - A surgical procedure that uses the cutting power of a laser beam to make bloodless cuts in tissue or to remove a surface lesion such as a tumor.