a. Normal Skin Pigments. Three elements are responsible for skin color:
melanin, a pigment in the epidermis; carotene, a pigment mostly in the dermis; and
blood in the capillaries found in the dermis. The amount of melanin causes the skin
color to vary from pale yellow to black. Melanin is found primarily in the basale and
spinosum layers of the skin and produced in cells called melanocytes. These cells are
located either just beneath or between the cells of the stratum basale. The number of
melanocytes is about the same in all races. Skin color differences in the races are due
to the amount of pigment the melanocytes produce and disperse. An individual without
pigment in the skin, hair, or pupils of the eyes is termed an albino. This person has
inherited an inability to produce melanin. In other people, melanin has a tendency to
form in patches called freckles. Carotene, a skin pigment found in Oriental people,
when mixed with melanin accounts for the yellowish hue of Oriental skin. The pink color
of Caucasian skin is due to blood in capillaries in the dermis without a heavy pigment in
the skin to mask the color. Blood in the capillaries close to the surface of the skin is
also responsible for the color of nailbeds, lining of the eyelids, oral mucose, and the
underlying vascular bed.
b. Abnormal Skin Pigments. Abnormal skin pigments include
hyperpigmentation, hypopigmentation, and erythema.
(1) Hyperpigmentation. Excessive pigmentation in the skin is termed
hyperpigmentation. Chronic adrenal insufficiency causes hyperpigmentation. A patient
may have increased pigmentation over his entire body, appearing to have a very good
tan year round. Areas of the body that may become noticeably darker include points of
pressure and friction such as elbows, knees, and scars; hair; and lines on the nails.
(2) Hypopigmentation. Not enough pigmentation in the skin is termed
hypopigmentation. The striking contrast between skin with pigment and skin without
pigment confused people in ancient times, who confused hypopigmentation with
leprosy. In the case of vitiligo, there is a loss of pigment in the skin, mucous
membranes, and hair bulbs.
(3) Erythema. This term refers to redness of the skin. An individual with a
fever will have erythema. Also, sunburned people and those with superficial infections
will have reddish-colored skin.
(4) Cyanosis. Cyanosis is a bluish discoloration of the skin, lips, and nail
beds caused by insufficient oxygen in the blood. Cyanosis can be caused by
congestive heart failure; pneumonia; or congenital heart disease with right-to-left