Skin Conditions: Overview

Skin conditions include various rashes, lesions, diseases, infections, injuries, growths, and cancers that affect the skin.

Alison's Story: Leaves of Three, Let Them Be

Did You Know?

Anatomy of the skin.

Anatomy of the skin.
Illustration by Frank Forney. © 2016 Cengage Learning®.

Alison loved to take long walks in the woods in the summer, but one day she developed a streaky rash two days after she had gone on a hike. At first, her skin was red and swollen in spots. Soon little blisters formed and began to itch intensely. Alison had developed contact dermatitis (DER-ma-TY-tis), an allergic response to touching urushiol (u-ROOshe-ol), an oily resin that is the allergen *

The most common symptoms of eczema are dry, itchy skin, and rashes on the face, inside the elbows, behind the knees, and on the hands and feet.

The most common symptoms of eczema are dry, itchy skin, and rashes on the face, inside the elbows, behind the knees, and on the hands and feet.

What Does the Skin Do?

The skin is the largest and most visible organ of the body. It also is one of the most complex, because it has so many different functions. The main job of the skin is to protect a person's inner organs, muscles, and tissues from harmful disease organisms, toxins, solar radiation, and other environmental hazards in the outside world. The skin acts as a shield against sun, wind, heat, cold, dryness, pollution, rain or snow, and fresh or saltwater fluid. All of these can injure the skin over time. In addition, the skin comes into contact with and helps protect the body from germs, allergens (substances that can cause allergic reactions) and irritants (harsh chemicals that can hurt the skin). The skin also has special nerve endings that alert the brain to the presence of heat, cold, and pain.

Names for Common Skin Lesions

The following are medical terms for some common lesions (LEE-zhuns), the general medical term for skin spots and bumps:

  • Comedo (KOM-ee-do): a clogged hair follicle in the skin, which may appear as a blackhead, whitehead, or pimple. The plural form is comedones (koh-mi-DOH-nez). Example: acne.
  • Macule (MAK-yool): a small flat colored spot. Example: freckles.
  • Papule (PAP-yool): a small solid elevation of the skin that usually occurs in clusters and often accompanies rashes.
  • Plaque (PLAK): a large raised patch of skin. Example: psoriasis.
  • Pustule (PUS-tyool): a pimple filled with pus. Example: acne.
  • Wheal (WEEL): a short-lasting swollen bump. Example: hives.

It is not surprising that many disorders can affect an organ so big and complicated. Allergens and irritants can make the skin break out in a rash. Dermatitis is a general term for red, inflamed skin that results from a variety of causes. There can also be problems in the way the skin functions. For example, it can make too much oil, leading to acne * . If the skin makes too many new cells, the result can be psoriasis (so-RY--a-sis). If the skin makes too little or too much coloring matter, called pigment, the result can be patches of abnormally light skin (hypopigmentation) or dark skin (hyperpigmentation).

The skin can also be injured by solar radiation, as in sunburn, and by viral infections like cold sores. Other kinds of skin infections are caused by bacteria * and fungi * . In addition, the skin can be affected by both noncancerous growths like birthmarks, and malignant growths like skin cancers. Last, the aging process causes skin problems in older adults that range from wrinkles and dryness to thinning of the skin and bruising more easily.

What Are Some Common Skin Problems?

Skin problems are so common in the general population that it is unusual for a person never to have had one. The following are some of the most common skin problems seen by dermatologists (DER-ma-TOL-o-jists), doctors who specialize in treating skin problems:


Books and Articles

Fischer, Karen. The Eczema Diet: Discover How To Stop & Prevent the Itch of Eczema through Diet & Nutrition. Toronto, ON: Robert Rose Publishing, 2013.

Lees, Mark. Skin Care: Beyond the Basics. 4th edition. Boston: Milday/Cengage Learning, 2012.

Weller, Richard B., Hamish J.A. Hunter, and Margaret W. Mann, eds. Clinical Dermatology. 5th ed. Hoboken, NJ: John Wiley and Sons, 2015.


American Academy of Dermatology. “Acne.” (accessed April 9, 2016).

Centers for Disease Control and Prevention. “Psoriasis.” (accessed July 10, 2016).

MedlinePlus. “Psoriasis.” U.S. National Library of Medicine, National Institutes of Health. (accessed July 10, 2016).


American Academy of Dermatology. PO Box 4014, Schaumburg, IL 60168-4014. Toll-free: 866-503-7546. Website: (accessed July 10, 2016).

American Society for Dermatologic Surgery. 5550 Meadowbrook Dr., Suite 120, Rolling Meadows, IL 60008. Telephone: 847-956-0900. Website: (accessed July 10, 2016).

National Institute of Arthritis and Musculoskeletal and Skin Diseases. 1 AMS Cir., Bethesda, MD 20892-3675. Telephone: 301-495-4484. Website: (accessed July 10, 2016).

* allergens are substances that provoke a response by the body's immune system or cause a hypersensitive reaction.

* acne (AK-nee) is a condition in which pimples, blackheads, whiteheads, and sometimes deeper lesions occur on the skin.

* bacteria (bak-TEER-ee-a) are single-celled microorganisms which typically reproduce by cell division. Some, but not all, types of bacteria can cause disease in humans. Many types can live in the body without causing harm.

* fungus (FUN-gus) is a microorganism that can grow in or on the body, causing infections of internal organs or of the skin, hair, and nails. The plural form is fungi (FUNG-eye).

* benign (be-NINE) refers to a condition that is not cancerous or serious and will probably improve, go away, or not get worse.

* virus (VV-rus) is a tiny infectious agent that can cause diseases. A virus can reproduce only within the cells it infects.

* histamine (HIS-tuh-meen) is a substance released by the body during inflammation. It causes blood vessels to expand and makes it easier for fluid and other substances to pass through vessel walls.

* immune system (im-YOON) is the system of the body composed of specialized cells and the substances they produce that protect the body against disease-causing germs.

* ultraviolet light is a wavelength of light beyond visible light. On the spectrum of light, it falls between the violet end of visible light and x-rays.

  This information is not a tool for self-diagnosis or a substitute for professional care.