NCCN Guidelines for Patients® | Melanoma - page 9

NCCN Guidelines for Patients
®
Melanoma, Version 1.2014
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Epidermis
The main job of the epidermis is to protect the body
and help control body temperature. It is made up of
four types of cells, including melanocytes.
Melanocytes are located at the bottom of the
epidermis. These cells make melanin, which spreads
to the top of the epidermis and gives skin its color.
People with darker skin have the same number of
melanocytes as people with lighter skin. The darkness
of skin is based on how much melanin is made by the
melanocytes. Higher levels of melanin cause the skin
to be darker.
Dermis
The dermis is much thicker than the epidermis. It
contains hair roots, blood vessels, lymph vessels,
glands, and nerve endings. Blood and lymph vessels
in the dermis bring nutrients to the dermis and
epidermis. Glands make fluids or chemicals the body
needs. Connective tissue holds all these structures in
place and allows the skin to stretch.
Under the dermis is the subcutaneous tissue.
Subcutaneous means “below the skin.” It is mostly
made of fat and connective tissue. It is not part of the
skin but connects the skin to muscles and bones. It
also saves body heat, stores energy, and absorbs
shock to protect the body from injury.
What is melanoma skin cancer?
Cells are the building blocks that form tissue in the
body. Genes are the instructions in cells for making
new cells and controlling how cells behave. Abnormal
changes (mutations) in genes can turn normal cells
into cancer cells. Normal cells divide to make new
cells. New cells are made as the body needs them to
replace injured or dying cells. Normal cells stay in one
place and do not spread to other parts of the body.
When normal cells grow old or get damaged, they die.
Cancer cells do not do this. Cancer cells don’t stay
in place as they should. Cancer cells make new cells
that aren’t needed and don’t die quickly when old or
damaged. Over time, cancer cells grow and divide
enough to form a tumor.
See Figure 2.
The first tumor
formed by the overgrowth of cancer cells is called the
primary tumor.
Figure 2. Normal versus cancer
cell growth
Normal cells divide to make
new cells as the body needs
them. Normal cells die once
they get old or damaged.
Cancer cells make new cells
that aren’t needed and don’t die
quickly when old or damaged.
Illustration Copyright © 2014 Nucleus Medical Media, All rights reserved.
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About melanoma
What is melanoma skin cancer?
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