Glossary of Skin Terms
And other skin conditions
acne – a chronic disorder of the hair follicles and sebaceous glands. Acne is characterized by black heads, pimple outbreaks, cysts, infected abscesses, and sometimes scarring. Learn more...
albinism – a rare, inherited disorder characterized by a total lack of melanin (skin pigment) in the skin.
allergy – an abnormally high sensitivity to certain substances, such as pollens, foods, or microorganisms. Common indications of allergy may include sneezing, itching, and skin rashes.
alpha hydroxy acids (AHAs) - alpha hydroxy acids are derived from fruit and milk sugars. The most commonly used alpha hydroxy acids are glycolic acid and lactic acid because they have a special ability to penetrate the skin. They also have the most scientific data on their effectiveness and side effects. The following are the 5 major types of alpha hydroxy acids found in skin-care products and their sources:
glycolic acid - sugar cane
lactic acid - milk
malic acid - apples and pears
citric acid - oranges and lemons
tartaric acid - grapes
angioma – a benign tumor in the skin, made up of blood or lymph vessels.
atopic dermatitis (atopic eczema or eczema) - a name given to a stubborn, itchy rash that occurs in certain people with sensitive or irritable skin. Eczema is common in infants and young children, and may disappear before adulthood. Eczema may clear for years, only to reappear later--often on the hands. Learn more...
atrophic skin – skin that is thin and wrinkled.
basal cells – these cells are found in the outer layer of skin. Basal cells are responsible for producing the squamous cells in the skin.
basal cell carcinoma – the most common form of skin cancer, characterized by small, shiny, raised bumps on the skin that may bleed.
bed sores – ulcers that occur on areas of the skin that are under pressure from lying in bed, sitting in wheelchairs, wearing a cast, or being immobile for a long period of time.
birth marks – areas of discolored and/or raised skin that are present at birth or shortly afterward.
biopsy – the procedure of removing tissue for examination under a microscope.
blackhead (or open comedo ) - a blocked pore in which the "plug" enlarges and pushes through the surface of the skin. The plug's dark appearance is not due to dirt, but rather to a buildup of melanin, the skin's dark pigment.
blister – a fluid-filled bump.
boil – tender, swollen areas that form around hair follicles.
candidiasis (also called yeast infection) – a skin infection caused by yeast that can occur in the skin folds, the navel, vagina, penis, mouth, and nail beds.
carbuncles – clusters of boils on the skin.
cavernous hemangioma – a raised, red or purple mark in the skin, made up of enlarged blood vessels.
cellulitis – a bacterial infection of the skin that is characterized by swelling and tenderness.
cold sore – small blisters around and in the mouth caused by the herpes simplex virus.
collagen – a protein produced by skin cells that provide strength and resilience to the skin.
comedo (plural: comedones ) - when dead skin cells mix with sebum and get trapped in the opening of a follicle, this is a comedo — the raw material for every kind of acne lesion. It acts like cork in a bottle, trapping dirt, bacteria and sebum inside the follicle, eventually resulting in an acne lesion.
comedogenic - substances that are likely to clog pores.
creeping eruption – a skin infection caused by hookworms that is characterized by severe itching.
crust (also called scab) – a formation of dried blood, pus, or other skin fluid over a break in the skin.
cryosurgery – a surgery technique that uses liquid nitrogen to freeze the skin.
cyst – a deep lesion that is filled with pus. An abnormal saclike structure that develops in the body and is filled with fluid or semisolid material.
darier disease - a stubborn rash which usually runs in families. The rash often starts when one is a teenager. It most commonly affects the chest, neck, back, ears, forehead, and groin, but may involve other body areas. At times the rash will cause a bad odor. This disease can also cause the fingernails to be fragile at the tips causing V-shaped notches at the end of the nails.
dermatitis – a number of skin conditions that inflame the skin.
dermatofibroma – small, red or brown bumps in the skin.
dermis – the middle layer of skin, which is made up of blood vessels, lymph vessels, hair follicles, and sweat glands.
dermoid cyst – a benign tumor made up of hairs, sweat glands, and sebaceous glands.
eczema - chronic itchy rash most commonly on face, back of knees, crook of elbows; dry thickened scaly skin or sometimes tiny red bumps that may ooze or become infected if scratched. Most common in families with history of allergies or asthma. Learn more...
epidermis – the outer layer of skin, which is made up of the horny layer, squamous cells and basal cells.
erysipelas – a skin infection that usually affects the arms, legs, or face, characterized by shiny, red areas, small blisters, and swollen lymph nodes.
erythema – redness of the skin caused by dilatation and congestion of the capillaries, often a sign of inflammation or infection.
erythema multiforme – a skin condition characterized by symmetrically positioned, red, raised skin areas all over the body.
erythema nodosum – a skin condition, characterized by red bumps that usually appear on the shins.
erythrasma – a skin infection of the top layer of skin characterized by irregular pink patches that turn to brown scales.
excoriation – a hollowed-out or linear area of the skin covered by a crust.
facial blushing (FB) - a sudden reddening of the face, neck and occasionally, upper chest. People refer FB as a sudden redness appearing after a high level of anxiety.
fifth disease - red cheeks that look as if they've been slapped; lacy red rash may appear on trunk and extremities; rash may be itchy; sometimes a slight fever, achiness; illness lasts about 7 to 10 days. Most common in preschool and school-aged children, (sometimes occurs in adults).
flushing - refered to as a longer lasting redness of the face, neck and occasionally, upper chest caused by alcohol, migraine headaches, fever, sudden temperature changes,cramps, anxiety and more.
folliculitis – an inflammation of the hair follicles due to an infection.
freckles – darkened, flat spots that typically appear only on sun-exposed areas of skin.
granuloma annulare – a chronic skin condition characterized by small, raised bumps that form a ring with a normal or sunken center.
hair follicle - a tubular infolding of the epidermis containing the root of a hair.
herpes zoster (also called shingles) – a common viral infection of the nerves, characterized by a painful skin rash of small blisters anywhere on the body.
hives (also called wheals) – a pink swelling of the skin. A skin condition characterized by intensely itching welts and caused by an allergic reaction to internal or external agents, an infection, or a nervous condition. Also called nettle rash, urticaria.
hyperhidrosis (facial blushing) - a medical term for excessive sweating. The problem may be limited to the armpits, but often the palms and soles of feet sweat excessively also. Excessive sweating becomes noticeable after puberty. Stressful situations such as examinations, job interviews, or an important date will aggravate the sweating. Most over-the-counter antiperspirants do not control hyperhidrosis.
hyperkeratinization - a disorder of the cells lining the inside of a hair follicle. It is the normal function of these cells to detach from the lining and attach to the growing hair, and die while converting themselves to contain keratin, so becoming a part of the hair.
hyperkeratosis - hypertrophy of the cornea or the horny layer of the skin. Also called hyperkeratinization.
ichthyosis - a skin disorder which causes the formation of dry, fish-like scales on the skin's surface. The condition often begins in early childhood and is usually lifelong. People with ichthyosis have a defect in their skin which causes it to lose moisture. We do not know what this defect is.
impetigo – a skin infection characterized by pus-filled blisters.
keloids – smooth, pink, raised, fibrous growths on the skin that form over healed wounds.
keratin - a tough, insoluble protein substance that is the chief structural constituent of hair, nails, horns, and hooves.
keratinization - organic process by which keratin is deposited in cells and the cells become horny (as in nails and hair).
keratinocytes (also called squamous cells) – these are the primary cell types found in the epidermis -- the outer layer of skin.
keratoacanthomas – round, flesh-colored growths with craters that contain a pasty material.
keratolytics - these are products which help to loosen superficial skin and allow it to be washed away more easily. Examples of keratolytics include beta hydroxy acids.
keratosis - excessive growth of horny tissue of the skin; a skin condition marked by an overgrowth of layers of horny skin.
keratosis pilaris – a very common genetic follicular disease manifested by the appearance of rough bumps on the skin. Primarily, it appears on the back and outer sides of the upper arms, but can also occur on thighs and buttocks or any body part except palms or soles. Learn more...
There are several different types of keratosis pilaris, including keratosis pilaris rubra (red, inflamed bumps), alba (rough, bumpy skin with no irritation), rubra faceii (reddish rash on the cheeks) and related disorders.
keratosis pilaris rubra faceii (KPRF) - reddish rash on the cheeks (blushed look). KPRF is characterized by redness (erythema) and the presence of rough bumpiness (follicular spines) which may begin at birth or during childhood or adolescence. Learn more...
lice – tiny insects that can infest the skin; characterized by intense itching.
lichenification – skin that has thickened.
lipomas – round or oval lumps under the skin caused by fatty deposits.
lymphangioma – a raised, yellow-tan or red mark in the skin, made up of enlarged lymphatic vessels.
macular stains (also called angel’s kisses or stork bites) – faint, red marks that appear in the skin at birth. Angel’s kisses are marks on the forehead and eyelids. Stork bites are marks on the back of the neck.
macule – the smaller version of a patch -- a flat discolored spot.
malignant melanoma – a rare, but deadly, skin cancer that begins as a mole that turns cancerous.
melanocytes - cells present in the epidermis that produce melanin (skin pigment).
milia - tiny cysts found mostly in the area around the eyes. They are hard to the touch and deep in the skin. Milia may last for weeks or even months; if they are particularly troublesome to you, consult your dermatologist for professional, safe removal.
moles – small skin marks caused by pigment-producing cells in the skin.
mongolian spots – bluish-black marks on the lower back and buttocks; affects mainly African-American or Asian children.
nodule (also called papule) – a solid, raised bump.
noncomedogenic - substance that is not likely to clog the pores.
papule - a small, solid, usually inflammatory elevation of the skin that does not contain pus.
paronychia – a skin infection around a finger or toenail.
patch – a flat, discolored spot.
pilus (pilaris) - a hair or hairlike structure, especially on the surface of a cell or microorganism.
pityriasis rosea – a common skin condition characterized by scaly, pink, and inflamed skin.
port-wine stains (also called nevi flammeus) – permanent flat, pink, red, or purple marks on the skin.
prickly heat – a rash caused by trapped sweat under the skin.
psoriasis – a chronic skin condition characterized by inflamed, red, raised areas that develop silvery scales. Learn more...
pustule (also called pimple) – inflamed lesions that look like pink bumps.
pyogenic granuloma – red, brown, or bluish-black raised marks caused by excessive growth of capillaries.
raised bumps – bumps that stick out above the skin surface.
ringworm – a fungal skin infection characterized by ring-shaped, red, scaly, or blistery patches.
rosacea – a common skin condition characterized by redness, pimples, and broken blood vessels. Learn more...
salicylic acid – a keratolytic drug (a drug that removes the outer layer of skin) used to treat various skin conditions.
sarcoidosis – an inflammation of the lymph nodes and other organs.
scabies – an infestation of mites in the skin characterized by small pimples that itch.
scales – dead skin cells that look like flakes or dry skin.
sebaceous glands – glands in the skin that secrete oil to the surface of the skin.
seborrheic keratosis – flesh-colored, brown, or black wart-like spots.
skin tags – soft, small, flesh-colored skin flaps on the neck, armpits, or groin.
sloughing (SLUFF-ing) - part of the skin’s natural renewal process, sloughing is the act of shedding dead skin cells to make room for new ones. When cells die, they travel up the hair follicle and out onto the surface of the skin, where they are gradually rubbed away or released into the environment. Until we reach our early 30s, the sloughing and renewal process takes about 28 days. As we age the process begins to slow; by the time we reach our 40s, complete skin renewal may take more than 50 days.
spider angioma – a bright red mark with a distinct dark spot in the skin.
squamous cells – see keratinocytes.
squamous cell carcinoma – a form of skin cancer that affects about 20 percent of patients with skin cancer. This highly treatable cancer is characterized by red, scaly skin that becomes an open sore.
strawberry mark (also called capillary hemangioma) – a raised, strawberry red mark in the skin.
subcutis – the deepest layer of skin; consists of collagen and fat cells.
tinea versicolor – a common fungal skin infection characterized by white or light brown patches on the skin.
toxic epidermal necrolysis - a life-threatening skin disorder characterized by blistering and peeling of the top layer of skin.
tretinoin - a drug which is chemically related to vitamin A; used to treat acne and other scaly skin disorders.
urea - a water-soluble compound that is the major nitrogenous end product of protein metabolism and is the chief nitrogenous component of the urine in mammals and other organisms. Also called carbamide.
urticaria - a relatively common form of allergic reaction that causes hives.
urushiol – resin in poison ivy plants that causes a skin reaction.
vitiligo – smooth, white patches in the skin caused by the loss of pigment-producing cells.
wart – a noncancerous skin growth caused by a virus.