Dermatology Terms Explained

I hope this glossary of dermatology terms will help you familiarize yourself with some of the terms used in our articles as well as terms used by your dermatologist.

This glossary has two parts. The first covers dermatology conditions, like acne or rosacea. The second explains common terms from dermatology in general.

Dermatology Conditions

Acne / Acne Vulgaris – A skin condition characterized by plugging and inflammation involving the hair follicles and sebaceous glands. Acne comes in many forms including blackheads, whiteheads, papules, pustules, nodules, cysts. Scarring may result from several different types of acne.  Learn more about acne from dermatologist Dr. Brandith Irwin.

Contact dermatitis – An allergic reaction to something that has touched your skin. Poison ivy and poison oak are examples. You can become allergic to a product even though you have used it for many years. An irritant reaction is different and is not a true allergy even though it may look similar.

Dermatitis – Irritation or inflammation of the skin. Dermatitis is a general term that refers to an itchy red rash, and is sometimes called eczema. There are about 20 different types of dermatitis.

Eczema – See dermatitis.

Edema – An abnormal accumulation of fluid, usually from the lymph system, which causes swelling and puffiness.

Folliculitis – Inflammation of the hair follicles, which can be due to irritation, infections, infections or other causes.

Hyperkeratosis – Excessive buildup of skin cells that, combined with sebum and trapped bacteria, creates a plug in hair follicles that results in acne lesions.

Hyperpigmentation – Abnormal darkening of the skin that can follow inflammation, sun exposure or skin injury of any kind and is caused by more melanin (the brown color in our skin) in a particular spot. Hyperpigmentation can also result from hormones and pregnancy (usually called melasma) combined with sun exposure. Hyperpigmentation from inflammation is easier to treat than melasma.

Hypertrophic scar – Scars that bulge outward like hard lumps. The word hypertrophy means “enlargement” or “overgrowth”.

Inflammation – A reaction of the skin to disease or injury. Inflammation usually shows up in the skin as redness, tenderness, itching or rough texture.

Keloid – Large scar whose size goes far beyond what would be expected. Most often occurs in the earlobes of teenagers after ear piercing but can occur anywhere. These can be itchy and tender to touch.

Keratosis Pilaris (KP) – A usually inherited condition of rough patches that are sometimes mistaken for acne. Some say KP also resembles goose bumps and is sometimes called ‘chicken skin’. KP usually appears on the back of the upper arms and sometimes on the cheeks, buttocks or upper thighs.

Perioral dermatitis – Usually appears a small red bumps or red patches around the nose and mouth. There are several different causes of it and many doctors think it is a type of rosacea.

Postinflammatory hyperpigmentation – These dark spots are also called postinflammatory pigmentation, or PIP. The original insult or injury that causes PIP can be acne, a cut, a burn, or a rash. The dark spots are limited to the sites of previous inflammation.

Pseudofolliculitis barbae (razor bumps) – Acne-like lesions that occur mainly on the beard area of men of African heritage. This condition is due to ingrown hairs. It is best prevented by using special shaving creams and shaving techniques. In severe cases, the hair may need to be extracted for healing to occur.

Rhinophyma – An enlarged nose that results from the oil glands on the nose overgrowing. It is a feature of rosacea that is seen primarily in men.

Rosacea – Acne like condition characterized by redness, papules, and sometimes pustules in the center 1/3 of the face, including the chin in certain, usually groups with northern European ancestry. It is often mistaken for acne.  Learn more about Rosacea from Dr. Irwin.

Telangiectasia – The chronic dilation of groups of capillaries that causes red lines or spots on the skin. Most common around the nose.

General Dermatology Terms

Collagen – A protein that forms the chief constituent of the connective tissue and bones, and gives skin strength and durability. Age related declines in collagen production cause thinning of the skin, wrinkles, and sagging.. Collagen itself in skin creams in virtually useless but collagen can be stimulated by retinoids, Vitamin C and some other antioxidants, lasers and some injectibles.

Cosmeceutical – A skin care ingredient that actually alters the skin and its underlying health. The FDA does not require proof that these products work. It only requires proof that they won’t harm people. Cosmeceuticals are often combined with cosmetic ingredients in skin care products. Cosmeceuticals are not regulated in the same way drugs are.

Décolleté / Décolletage – The area in women from the base of the neck to the top of the bosom. This area is particularly prone to sun damage.

Dermis – Layer of the skin just beneath the epidermis. Contains collagen fibers, elastic fibers, hyaluronic acid, blood and lymphatic vessels, hair follicles, nerves, glands, and many other things. It is the “brains” of the skin. Also called cutis.

Elastin – A protein component of skin that helps maintain skin resilience and elasticity. When elastin is abundant and undamaged, the skin regains its shape after being folded or stretched.

Epidermis – Outer layer of the skin that lies on top of the dermis. It is the “barrier” layer of the skin and protects us from infectious agents, sunburn, becoming dehydrated, and many environmental insults. It also has most of the pigment making cells (melanocytes)

Fibroblasts – Cells that produce collagen and elastin which provide the structure of the middle layer of the skin called the dermis.

Free Radicals – Highly reactive atoms or molecules with an unpaired electron. Free radicals are created from many metabolic processes, inflammation and sun damage. They contain one or more unpaired electrons and scavenge, or steal, electrons from other molecules, thus damaging those molecules. In terms of your skin, free radicals can damage collagen and elastin. Antioxidants are substances which help to limit the damage from these unpaired electrons.

Keratin – Tough, fibrous protein that is inside the cells of the epidermis. Keratin is also a constituent of hair and nails. Keratinocytes (the cells in the epidermis) make keratin.

Keratinization – Is the process by which cells in the epidermis “mature.” As they mature, they move up through the layers of the epidermis and gradually lose the body of the cell leaving the hard keratin (stratum corneum) on the outer layer of the skin.

Keratinocytes – Make up the majority of the cells in the epidermis.

Keratinized Skin – When dead skin cells build up and cover up the newer skin underneath, leading to dull skin. As we get older this occurs more. There are many ways to gently remove the outer, dead skin layers.

Lesion – A mark in the skin, which in dermatology often refers to a sore, growth, blister, or any other type of tissue damage caused by disease or injury.

Melanin – Substance that gives the skin and hair its color and protects against UV radiation.

Melanocytes – The cells that produce the pigment melanin. This pigment colors our hair, skin, and eyes. Melanin is heavily concentrated in skin moles.

Noncomedogenic – A type of skin care product that doesn’t make acne worse or promote the formation of blackheads and whiteheads. Some skin care products contain petrolatum lanolin which are comedogenic and can promote blackheads and breakouts, just to name a few.

Photoaging – A term that refers to skin damage from the sun, often associated with brown spots (sun spots), leathery skin and broken or dilated blood vessels.

Propionibacterium Acnes (P. acnes) – These bacteria are an integral part of producing inflammatory lesions of acne. They live in the pilosebaceous (oil) glands of the skin.

Sebaceous Duct – Tiny tube that steers the sebum (and the dead skin cells it carries) from the sebaceous gland into the hair canal and out onto the surface of the skin.

Sebaceous Glands – Located in the dermis next to hair follicles, these are small, sack shaped glands that release sebum onto the hair and moisturize the skin.

Sebum – The semi fluid secretion of the sebaceous glands, consisting chiefly of fat, keratin, and cellular material.

SPF (Sun Protection Factor) – Currently, the SPF only refers to protection from UVB. It does not cover UVA. The FDA is working on a new system that will include both. In the meantime, consumers need to be sure their sunscreen contains a UVA blocker as well. Look for zinc, titanium, mexoryl, avobenzone/Parlsol. All sunscreens are currently labeled with an SPF that lets you know how long you can stay in the sun before burning. An SPF of 30, properly applied, blocks 90-95% of the UVB rays.

Stratum Corneum – Also know as the dead or horny layer, it is the outer-most layer of the epidermis. It is comprised of dead skin cells that protect deeper cells from damage, infection, and from drying out.

Subcutaneous Layer – Fatty layer of tissue located under the dermis and above muscle and fascia.

Topical Therapy – Something that is applied onto the skin, such as a cream, gel, or ointment.

T-Zone – The forehead, nose and chin. There are more oil glands in this area causing a greater tendency for breakouts, blackheads, whiteheads and other acne problems.

Dr. Irwin

Next, check out Which Types of Skin Care Products Do You Really Need? 

See Dr. Irwin’s expert answers to other reader’s questions on dermatology terms:
How many skin types do we have?