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BIOL 250: Human Anatomy
4: The Integumentary System
4.4: Diseases, Disorders, and Injuries of the Integumentary System

4.4: Diseases, Disorders, and Injuries of the Integumentary System

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Learning Objectives

Describe several different diseases and disorders of the skin

Describe the effect of injury to the skin and the process of healing

The integumentary system is susceptible to a variety of diseases, disorders, and injuries. These range from annoying but relatively benign bacterial or fungal infections that are categorized as disorders, to skin cancer and severe burns, which can be fatal. In this section, you will learn several of the most common skin conditions.

Diseases

One of the most talked about diseases is skin cancer. Cancer is a broad term that describes diseases caused by abnormal cells in the body dividing uncontrollably. Most cancers are identified by the organ or tissue in which the cancer originates. One common form of cancer is skin cancer. The Skin Cancer Foundation reports that one in five Americans will experience some type of skin cancer in their lifetime. The degradation of the ozone layer in the atmosphere and the resulting increase in exposure to UV radiation has contributed to its rise. Overexposure to UV radiation damages DNA, which can lead to the formation of cancerous lesions. Although melanin offers some protection against DNA damage from the sun, often it is not enough. The fact that cancers can also occur on areas of the body that are normally not exposed to UV radiation suggests that there are additional factors that can lead to cancerous lesions.

In general, cancers result from an accumulation of DNA mutations. These mutations can result in cell populations that do not die when they should and uncontrolled cell proliferation that leads to tumors. Although many tumors are benign (harmless), some produce cells that can mobilize and establish tumors in other organs of the body; this process is referred to as metastasis. Cancers are characterized by their ability to metastasize.

Basal Cell Carcinoma

Basal cell carcinoma is a form of cancer that affects the mitotically active stem cells in the stratum basale of the epidermis. It is the most common of all cancers that occur in the United States and is frequently found on the head, neck, arms, and back, which are areas that are most susceptible to long-term sun exposure. Although UV rays are the main culprit, exposure to other agents, such as radiation and arsenic, can also lead to this type of cancer. Wounds on the skin due to open sores, tattoos, burns, etc. may be predisposing factors as well. Basal cell carcinomas start in the stratum basale and usually spread along this boundary. At some point, they begin to grow toward the surface and become an uneven patch, bump, growth, or scar on the skin surface (Figure \(\PageIndex{1}\)). Like most cancers, basal cell carcinomas respond best to treatment when caught early. Treatment options include surgery, freezing (cryosurgery), and topical ointments (Mayo Clinic 2012).

Squamous Cell Carcinoma

Squamous cell carcinoma is a cancer that affects the keratinocytes of the stratum spinosum and presents as lesions commonly found on the scalp, ears, and hands (Figure \(\PageIndex{2}\)). It is the second most common skin cancer. The American Cancer Society reports that two of 10 skin cancers are squamous cell carcinomas, and it is more aggressive than basal cell carcinoma. If not removed, these carcinomas can metastasize. Surgery and radiation are used to cure squamous cell carcinoma.

Melanoma

A melanoma is a cancer characterized by the uncontrolled growth of melanocytes, the pigment-producing cells in the epidermis. Typically, a melanoma develops from a mole. It is the most fatal of all skin cancers, as it is highly metastatic and can be difficult to detect before it has spread to other organs. Melanomas usually appear as asymmetrical brown and black patches with uneven borders and a raised surface (Figure \(\PageIndex{3}\)). Treatment typically involves surgical excision and immunotherapy.

Doctors often give their patients the following ABCDE mnemonic to help with the diagnosis of early-stage melanoma. If you observe a mole on your body displaying these signs, consult a doctor.

Asymmetry – the two sides are not symmetrical
Borders – the edges are irregular in shape
Color – the color is varied shades of brown or black
Diameter – it is larger than 6 mm (0.24 in)
Evolving – its shape has changed

Some specialists cite the following additional signs for the most serious form, nodular melanoma:

Elevated – it is raised on the skin surface
Firm – it feels hard to the touch
Growing – it is getting larger

Skin Disorders

Two common skin disorders are eczema and acne. Eczema is an inflammatory condition and occurs in individuals of all ages. Acne involves the clogging of pores, which can lead to infection and inflammation, and is often seen in adolescents. Other disorders, not discussed here, include seborrheic dermatitis (on the scalp), psoriasis, cold sores, impetigo, scabies, hives, and warts.

Eczema

Eczema is an allergic reaction that manifests as dry, itchy patches of skin that resemble rashes (Figure \(\PageIndex{4}\)). It may be accompanied by swelling of the skin, flaking, and in severe cases, bleeding. Many who suffer from eczema have antibodies against dust mites in their blood, but the link between eczema and allergy to dust mites has not been proven. Symptoms are usually managed with moisturizers, corticosteroid creams, and immunosuppressants.

Acne

Acne is a skin disturbance that typically occurs on areas of the skin that are rich in sebaceous glands (face and back). It is most common along with the onset of puberty due to associated hormonal changes, but can also occur in infants and continue into adulthood. Hormones, such as androgens, stimulate the release of sebum. An overproduction and accumulation of sebum along with keratin can block hair follicles. This plug is initially white. The sebum, when oxidized by exposure to air, turns black. Acne results from infection by acne-causing bacteria (Propionibacterium and Staphylococcus), which can lead to redness and potential scarring due to the natural wound healing process (Figure \(\PageIndex{5}\)).

CAREER CONNECTION

Dermatologist

Have you ever had a skin rash that did not respond to over-the-counter creams, or a mole that you were concerned about? Dermatologists help patients with these types of problems and more, on a daily basis. Dermatologists are medical doctors who specialize in diagnosing and treating skin disorders. Like all medical doctors, dermatologists earn a medical degree and then complete several years of residency training. In addition, dermatologists may then participate in a dermatology fellowship or complete additional, specialized training in a dermatology practice. If practicing in the United States, dermatologists must pass the United States Medical Licensing Exam (USMLE), become licensed in their state of practice, and be certified by the American Board of Dermatology.

Most dermatologists work in a medical office or private-practice setting. They diagnose skin conditions and rashes, prescribe oral and topical medications to treat skin conditions, and may perform simple procedures, such as mole or wart removal. In addition, they may refer patients to an oncologist if skin cancer that has metastasized is suspected. Recently, cosmetic procedures have also become a prominent part of dermatology. Botox injections, laser treatments, and collagen and dermal filler injections are popular among patients, hoping to reduce the appearance of skin aging.

Dermatology is a competitive specialty in medicine. Limited openings in dermatology residency programs mean that many medical students compete for a few select spots. Dermatology is an appealing specialty to many prospective doctors, because unlike emergency room physicians or surgeons, dermatologists generally do not have to work excessive hours or be “on-call” weekends and holidays. Moreover, the popularity of cosmetic dermatology has made it a growing field with many lucrative opportunities. It is not unusual for dermatology clinics to market themselves exclusively as cosmetic dermatology centers, and for dermatologists to specialize exclusively in these procedures.

Consider visiting a dermatologist to talk about why he or she entered the field and what the field of dermatology is like. Visit this site for additional information.

Chapter Review

Skin cancer is a result of damage to the DNA of skin cells, often due to excessive exposure to UV radiation. Basal cell carcinoma and squamous cell carcinoma are highly curable, and arise from cells in the stratum basale and stratum spinosum, respectively. Melanoma is the most dangerous form of skin cancer, affecting melanocytes, which can spread/metastasize to other organs. Burns are an injury to the skin that occur as a result of exposure to extreme heat, radiation, or chemicals. First-degree and second-degree burns usually heal quickly, but third-degree burns can be fatal because they penetrate the full thickness of the skin. Scars occur when there is repair of skin damage. Fibroblasts generate scar tissue in the form of collagen, which forms a basket-weave pattern that looks different from normal skin.

Bedsores and stretch marks are the result of excessive pressure on the skin and underlying tissue. Bedsores are characterized by necrosis of tissue due to immobility, whereas stretch marks result from rapid growth. Eczema is an allergic reaction that manifests as a rash, and acne results from clogged sebaceous glands. Eczema and acne are usually long-term skin conditions that may be treated successfully in mild cases. Calluses and corns are the result of abrasive pressure on the skin.

Review Questions

Q. In general, skin cancers ________.

A. are easily treatable and not a major health concern

B. occur due to poor hygiene

C. can be reduced by limiting exposure to the sun

D. affect only the epidermis

Answer: C

Q. An individual has spent too much time sun bathing. Not only is his skin painful to touch, but small blisters have appeared in the affected area. This indicates that he has damaged which layers of his skin?

A. epidermis only

B. hypodermis only

C. epidermis and hypodermis

D. epidermis and dermis

Answer: D

Q. Squamous cell carcinomas are the second most common of the skin cancers and are capable of metastasizing if not treated. This cancer affects which cells?

A. basal cells of the stratum basale

B. melanocytes of the stratum basale

C. keratinocytes of the stratum spinosum

D. Langerhans cells of the stratum lucidum

Answer: C

Critical Thinking Questions

Q. Why do teenagers often experience acne?

A. Acne results from a blockage of sebaceous glands by sebum. The blockage causes blackheads to form, which are susceptible to infection. The infected tissue then becomes red and inflamed. Teenagers experience this at high rates because the sebaceous glands become active during puberty. Hormones that are especially active during puberty stimulate the release of sebum, leading in many cases to blockages.

References

American Cancer Society (US). Skin cancer: basal and squamous cell [Internet]. c2013 [cited 2012 Nov 1]. Available from: http://www.cancer.org/acs/groups/cid...003139-pdf.pdf.

Lucile Packard Children’s Hospital at Stanford (US). Classification and treatment of burns [Internet]. Palo Alto (CA). c2012 [cited 2012 Nov 1]. Available from: www.lpch.org/diseasehealthinf.../classify.html.

Mayo Clinic (US). Basal cell carcinoma [Internet]. Scottsdale (AZ); c2012 [cited 2012 Nov 1]. Available from: http://www.mayoclinic.com/health/bas...ents-and-drugs.

Beck, J. FYI: how much can a human body sweat before it runs out? Popular Science [Internet]. New York (NY); c2012 [cited 2012 Nov 1]. Available from:http://www.popsci.com/science/articl...at-it-runs-out.

Skin Cancer Foundation (US). Skin cancer facts [Internet]. New York (NY); c2013 [cited 2012 Nov 1]. Available from: http://www.skincancer.org/skin-cance...ncer-facts#top.

Glossary

acne: skin condition due to infected sebaceous glands

basal cell carcinoma: cancer that originates from basal cells in the epidermis of the skin

bedsore: sore on the skin that develops when regions of the body start necrotizing due to constant pressure and lack of blood supply; also called decubitis ulcers

callus: thickened area of skin that arises due to constant abrasion

corn: type of callus that is named for its shape and the elliptical motion of the abrasive force

eczema: skin condition due to an allergic reaction, which resembles a rash

first-degree burn: superficial burn that injures only the epidermis

fourth-degree burn: burn in which full thickness of the skin and underlying muscle and bone is damaged

keloid: type of scar that has layers raised above the skin surface

melanoma: type of skin cancer that originates from the melanocytes of the skin

metastasis: spread of cancer cells from a source to other parts of the body

scar: collagen-rich skin formed after the process of wound healing that is different from normal skin

second-degree burn: partial-thickness burn that injures the epidermis and a portion of the dermis

squamous cell carcinoma: type of skin cancer that originates from the stratum spinosum of the epidermis

stretch mark: mark formed on the skin due to a sudden growth spurt and expansion of the dermis beyond its elastic limits

third-degree burn: burn that penetrates and destroys the full thickness of the skin (epidermis and dermis)