Skin Cancer
Introduction, Types & Pictures
Skin cancer is a form of cancer that develops in the skin tissue. It
occurs when certain cells called malignant cells start to grow and divide
faster than normal resulting in tumors. There are 4 main types of skin
cancer:
- Basal cell carcinoma, (Non-melanoma)
- Squamous cell carcinoma (Non-melanoma) and
- Melanoma (Melanoma)
- Merkel Cell Carcinoma
The skin is the largest organ covering the entire surface of the body.
The skin plays several important functions like:
- Protection against heat, light, injuries, infections, bacteria and
pathogens
- Regulates body temperature
- Stores water, fat and vitamin D
- Prevents water loss
- Sensory perception
The skin structure is composed from three main layers:
| 1. Epidermis,
the outer, thin layer of skin. The epidermis is formed from four
layer of cells:
1). Stratum corneum is the first layer
of the epidermis that sheds continuously. This layer plays two
essential roles: protection against foreign substances that
can enter the body and prevents excessive fluid loss from the
body.
2). Keratinocytes layer (squamous cells)
is a thin, flat layer of cells (beneath the stratum corneum)
formed from squamous cells or keratinocytes.
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3). Basal layer is the deepest layer of the
epidermis formed from round cells called basal cells. The basal cells
undergo a continuous dividing process forming new keratinocytes that
replace the old ones maintaining the continuous shedding process of
the stratum corneum (the first layer of the epidermis).
4). Melanocytes. These cells can be located
into the lower layers of the skin and contain melanin, which is the
pigment that gives the skin its natural color. When the skin is exposed
to the Sun, these cells produce more melanin and the skin gets a darker
appearance.
2. Dermis is the middle layer of skin and contains the following:
blood and lymph vessels, hair follicles, sweat glands, collagen bundles,
fibroblasts, nerves, and pain and touch receptors. This layer of skin
is held together by the collagen.
3. Hypodermis is the deepest layer of skin and is formed from
a collagen network and fat cells (subcutaneous fat layer). It plays two
essential roles: conserves the heat of the body and protects the body
from injuries.
Skin cancer is the most common form of cancer in the
United States with basal cell and squamous cell being the most common
sub-types. The more dangerous melanoma is less common. Although anyone
can get skin cancer, it is more common in people over the age of 50, spend
a lot of time in the Sun, and in those who have light colored skin and
hair.
Types
Skin cancer can occur anywhere on the body, but more commonly develops
in areas that are more exposed to the sunlight like face skin, neck skin,
hands or arms skin.
There are four types of skin cancer:
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Basal cell carcinoma is the most common
type of skin cancer. It develops in the deepest layer of the
epidermis. It usually occurs in areas exposed more often to
the sun like the nose. Initially, the tumor looks like a small,
smooth and pearly bump or as a flat and firm scar. This type
of cancer can spread to adjacent areas but only rarely spreads
to other parts of the body. There are 12 subtypes of basal
cell carcinoma which more information can be found here.
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Squamous cell carcinoma is another common
type of skin cancer that develops in the keratinocytes layer
of the epidermis. It usually occurs in those regions of
the skin more exposed to the sun, like ears, lower lip, and
back of the hands, or in areas of the skin that have been
burned or exposed to chemicals and radiation. This type of
cancer appears as a red firm or scaly bump that can bleed
or form a crust.
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Melanoma is the most virulent form of skin cancer.
It occurs in the lower layer of the epidermis when melanocytes (the
pigment cells) become malignant and grow and divide abnormally. This
type of cancer can spread to other areas and organs of the body through
the lymph vessels (phase called metastatic melanoma) if not treated.
There are six morphologic types of melanoma:
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Superficial spread melanoma is
the most common type of melanoma and follows a long growth pattern
before it becomes invasive. This type of cancer looks like a brown,
flat or slight lesion with irregular asymmetric borders and with
a black, blue or pink discoloration. It can occur anywhere on the
body, especially in the neck and head area, or on the male's trunk
and female's lower extremities.
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Nodular melanoma is a less
common type of melanoma that occurs and can spread to nearby areas
extremely fast. It appear as a dark brown to black papule or dome-shape
nodule. This type of cancer can occur anywhere on the body, especially
on the male's trunk.
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Acral-lentiginous melanoma is
a rare form of melanoma but common for dark-skinned people. It follows
a progressive growth pattern and is an aggressive type of melanoma.
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Lentigo maligna melanoma
is another rare form of melanoma and follows a long growth pattern
before it becomes invasive. Initially, it appears as a lesion larger
than 3 cm and becomes dark brown to black color or as a blue-black
nodes during the invasive phase. This type of melanoma is caused
by sun exposure and occurs in those regions of the skin that are
more exposed to the sun light.
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Amelanotic melanoma is
a very rare form of melanoma and is difficult to diagnose due to
the lack of pigmentation.
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Desmoplastic melanoma is
another rare form of melanoma. It is an aggressive type of cancer
and is difficult to diagnose. It is more common in elderly patients
and usually occurs on the head or neck area.
4. Merkel Cell Carcinoma: This is a rare and highly
aggressive form of skin cancer.
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Article by Alina Morrow, MS
Medical Writer
OmniMedicalSearch.com
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Basal Cell Carcinoma after treatment with a topical chemotherapy
called flouracil. See
More: Basal Cell
Carcinoma Pictures Here
Basal Cell Carcinoma on the chest of a 58 year-old woman
after treatment with a topical chemotherapy called flouracil.
Hole left after skin cancer was cut out.
Two-inch long incision with stitches following the removal
of skin cancer from a woman's arm.
Melanoma skin cancer with surgery lines on the chest of
a male patient.
Microscopic photo of melanoma skin cancer cells.
Suspicous skin mole that should be examined by a dermatologist.
Suspcious skin mole that should be examined by a dermatologist.
Artist rendering of different cancer cells.
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