knowledge of the variation of the skin's color aids effective examination as well as makes you (the doctor) smart enough not to give wrong diagnosis. In general, color changes of significance include pallor, cyanosis, erythema, plethora, ecchymosis, petechiae and jaundice.
Pallor and cyanosis
The skin receives its pigmented color of yellow, brown, and black melanin and its shades of red or blue from the color of hemoglobin. Oxygenated hemoglobin in the superficial capillaries of the dermis gives a rosy, pink glow. Reduced (deoxygenated) hemoglobin reflects a bluish tone, through the skin, called cyanosis, which is evident when reduced hemoglobin levels reach 5mg/dl of blood or more, regardless of the total hemoglobin. In general, the darker the skin pigmentation is, the greater the amount of deoxygenated hemoglobin must be for cyanosis to be evident.
Pallor or paleness, is evident as a loss of the rosy glow in light-skinned individuals, an ashen-gray appearance in black-skinned children. And a more yellowish brown color in brown-skinned people. It may be a sign of anemia, chronic disease, edema, or shock. However, it may be a normal complexion characteristic or an indication of indoor living.
Pallor or cyanosis is most evident in the palpebral conjunctiva (lower eyelid), nail beds, earlobes (mainly for light-skinned children), lips, oral membranes, soles and palms. Pallor or cyanosis can be compared to the color change normally produced by blanching. For example, in non-pigmented nails, pressing down on the free edge of the nail on the index or middle finger of a child with good skin color produce marked blanching or whitening as compared to the return blood flow. In a child with pallor the difference in color change will be slight. The blanching color change can be observed in dark-skinned individuals by gently applying pressure to their lips or gums.
Erythema, or redness of the skin, may be the result of increased temperature from climatic conditions, local inflammation, or infection. It may also appear as a sign of skin irritation, allergy, or other dermatoses. The degree of redness reflects the amount of increased blood flow to the area. The doctor notes any reddening and describes its location, size, presence or warmth, itching, type of distribution (diffuse, clearly circumscribed, parallel to a vein, and so on) and the presence of characteristic lesions, such as maculae, papules, or vesicles. Because erythema is much more difficult to assess in darkly pigmented individuals the doctor must rely heavily on careful palpating the area for the evidence of associated signs, such as warmth or skin lesions. Primary lesions appear on the non-damaged skin. Secondary lesions come out after primary ones.
Plethora is also seen as redness of the skin but it is caused by increased numbers of red blood cells as a compensatory response to chronic hypoxia. Intense redness of the lips or cheeks is observed.
Ecchymosis and Petechiae
Ecchymosis and petehiae are caused by extravasation or hemorrhage of blood into the skin, the only difference between the two is in size. Ecchymoses are large, diffuse areas, usually black and blue in color, and are typically the result of accidental injuries in healthy, active children. Since ecchymotic areas can be indicative of systemic disorders or of child maltreatment. The doctor should always investigate the reported cause of the bruises, especially when they are located in suspicious areas, such as the back or buttocks, rather than on the knees, shins, elbows, or forearms.
Petechiae are small, distinct pinpoint hemorrhages 2mm or less in size, which can denote some type of blood disorder, such as decreased platelets in leukemia. Because of their size, ecchymoses are more readily observed than are petechiae, which may only be visible in the areas of very light-colored skin, such as the buttocks, abdomen, and inner surfaces of the arms or legs. They are usually invisible in heavily pigmented skin, except in the oral mucosa, the palpebral conjusctiva of the eyelids, and the bulbar conjunctiva covering the eyeball.
The doctor can distinguish the areas of the erythema from ecchymosis or petechiae by blanching the skin. Since erythema is the result of increased blood flow to the area, exerting pressure will momentarily empty the engorged vessels and produced by blood leaking into tissue spaces, blanching will not occur.
Effective examination of the skin color can be achieved if you put these few points into consideration.