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Diseases and Disorders of the Scalp

May 30, 2008 (Revised 7-8-08)

James L. Breeling

Introduction
Seborrhea of the Scalp
Seborrheic Dermatitis of the Scalp
Fungal Infections of the Scalp (Ringworm)
Bacterial and Viral Infections of the Scalp
Head Lice
Psoriasis of the Scalp
Diseases of Autoimmune or Unknown Origin Affecting the Scalp
Acne of the Scalp
Allergic and Irritant Contact Dermatitis of the Scalp



Introduction

The desire to have healthy, attractive hair can be undercut if a skin disorder produces a debilitated condition of the scalp. Diseases and disorders of the scalp can cause scalp conditions that include excessive oiliness, excessive flaking, inflammation, patchy scabbing and intense pruritus (itchiness).

Some of these disorders are infections, some are allergic reactions or other immune responses, and all involve some degree of inflammation (see What is Inflammation?). Some are conditions confined to the scalp (e.g., tinea capitis, also called ringworm), some are scalp manifestations of a more general or systemic condition (e.g., psoriasis).

Each condition has specific symptoms, but the presentation of symptoms may be confusingly similar between one condition and another (for example, seborrheic dermatitis of the scalp and psoriasis of the scalp have a number of symptoms and clinical features in common). Some conditions, or milder forms of conditions, can be managed by home care with over-the-counter medications. More severe symptoms, and systemic conditions such as psoriasis, should be treated by a dermatologist or other physician with knowledge and experience in treating skin diseases.



What Is Inflammation?

Inflammation is one of the body's principal defense systems against invasion by micro-organisms or injury by thermal, chemical or physical trauma. The successful endpoint of inflammation is healing; a simple example is inflammatory response to a splinter in the finger, resulting in expulsion of the splinter and healing of the wound.

Inflammation is orchestrated by the body's immune system. When immune surveillance detects an event it interprets as invasion or injury, a cascade of inflammatory precursors is set into motion. When the reason for the inflammatory response is resolved, the inflammatory response is concluded under control of the immune system.

The inflammatory response can go awry, however, to the point that inflammation becomes a disease in itself. For example:

  • Inflammatory response to a local bacterial infection spirals out of control, becoming a body-wide inflammation of all major organs that ends in critical illness or even death.


  • Inflammation in response to local insult proceeds to a persistent, chronic inflammatory state that may be associated with arthritis, heart disease, complications of psoriasis and a number of other chronic conditions.


  • How and why regulation of the inflammatory response sometimes fails is a subject of intense medical investigation.



    Bibliography


  • Tracey KJ. The inflammatory reflex (review). Nature 2002; 420:853-859.


  • Beutler B. Key inflammatory and stress pathways in critical illness-the central role of Toll-like receptors. Critical Care 2003; 7:39-46.


  • Irwin RS, Cerra FB, Rippe JM (eds). Irwin and Rippe's Intensive Care Medicine, 5th ed. Hagerstown, MD: Lippincott, Williams & Wilkins; 2003.




  • Seborrhea of the Scalp

    Sebum is the oily substance secreted by sebaceous glands in the skin. This "skin oil" has a protective function of keeping skin from losing moisture and becoming excessively dry, and providing a layer of defense against potentially infectious micro-organisms. Seborrhea is the medical term for excessive production of sebum, but the definition of "excessive" varies with the age and gender of the individual. Sebum production is influenced by age, sex and hormonal status.

    Because the largest sebaceous glands are on the face, scalp and groin, these areas are subject to become excessively oily due to seborrhea. All sebaceous glands distribute sebum through a connection to hair follicles, making sebaceous glands and hair follicles the functional units for dispensing sebum to the surface of the skin. The anatomical proximity of sebaceous glands and hair follicles explains why oily skin and oily hair usually occur together in seborrhea.

    Sebum production is largely under hormonal control, with the androgenic male hormones playing a central role in both males and females. As males begin to mature into adulthood at about age 13 to 16, androgen levels rise and sebum production increases. Sebum production reaches its highest level in males at about 20, then slowly declines but remains higher than in healthy females throughout life. Sebum production declines markedly in females after menopause.

    The defining symptom and major complaint associated with seborrhea of the scalp is excessive oiliness of the scalp and hair. A greasy-looking scalp is unsightly and excessively oily hair is both unattractive and difficult to style. In males-young males especially-seborrhea often occurs in conjunction with acne (see Acne of the Scalp). Seborrhea can often be managed at home by keeping the scalp clean with shampooing as often as necessary. Some over-the-counter shampoos are labeled for use on oily hair. Seborrhea that is resistant to home treatment should be referred to a physician for examination. Medical treatment may include a medication that reduces sebum synthesis. Additional examination may be necessary if an underlying hormonal dysfunction is suspected.



    Seborrheic Dermatitis of the Scalp

    Excessive oiliness of the skin is a feature of seborrheic dermatitis, but the condition is not a disorder of sebum production. The underlying cause of seborrheic dermatitis is unknown. It shares some features with psoriasis (see Psoriasis of the Scalp), and some investigators have proposed that seborrheic dermatitis and psoriasis may have some genetic predispositions in common. Other investigators have made a case for fungal infection being responsible for the major features of seborrheic dermatitis. Excessive skin oiliness may be a predisposing factor.

    Seborrheic dermatitis is seen most frequently in infants up to 3 months old (when the condition is called "cradle cap"), and in adults over age 30-40, more commonly in men than in women. It is seen frequently in persons infected with the human immunodeficiency virus (HIV), indicating that immune system dysfunction is an underlying or contributing cause of seborrheic dermatitis. An immune dysfunction is also suggested by the frequency of secondary fungal and bacterial infections.

    The symptoms and clinical features of seborrheic dermatitis of the scalp include:

  • Flaking of whitish to brownish scales from the scalp, the condition commonly called dandruff (see Dandruff);


  • Greasy crusts on the scalp that become greasy yellow-to-brown scales when they fall off;


  • Inflamed, boggy patches underlying the crusts;


  • Extension of inflammation to the ears, eyelids, eyebrows, cheeks and nostrils; and,


  • Moderate to intense pruritus (itchiness) that may lead the patient to scratch vigorously, causing injury and additional inflammation (see What is Inflammation?), as well as openings for secondary infection.


  • Mild to moderate seborrheic dermatitis may be kept in check by frequent shampooing with over-the-counter anti-dandruff shampoos. More severe disease requires medical attention appropriate to the condition; seborrheic dermatitis and psoriasis of the scalp share many features and must be differentiated before treatment.

    When a diagnosis of seborrheic dermatitis is confirmed, medical treatment may include topical corticosteroids to reduce inflammation, shampoos containing anti-inflammatory and anti-microbial ingredients, and topical or systemic antibiotics or anti-fungal agents to treat infection.



    Fungal Infection of the Scalp (Ringworm)

    The fungal infection of the scalp most recognizable by its common name is "ringworm" although the infecting organism is a fungus, not a worm. Dozens of fungi are capable of infecting the scalp, the incidence of the fungi in scalp infections varying in different geographic areas and climate zones of the world.

    Tinea capitis (commonly called ringworm of the scalp) is the most common fungal scalp infection seen in the United States and other temperate-zone countries. The description "ringworm of the scalp" derives from Latin root words: "tinea" is a Latin root word for "worm", and "capitis" derives from the Latin root for "head".

    No single fungal organism is the cause of tinea capitis. A number of fungi in the broad generic categories called Microsporum and Trichophyton are the most frequent infecting organisms. The infection is easily spread from person to person by contact with hairs shed from an infected scalp, or by contact with a pillow, hat, etc., where the infecting fungi have been deposited. Because schools are a frequent site of transmission, tinea capitis has a high incidence among school children.

    Three patterns of tinea capitis are identified:

  • Noninflammatory, with hairs made to appear gray by their dusting of fungi, reddish patches on scalp skin, some scaling of skin around the reddish patches, and breakage of hairs just above the hair follicles;


  • Inflammatory, with intensely inflamed hair follicles, moist patches of intense inflammation and broken hairs, oozing pus, intense itching and pain; and,


  • "Black dot" tinea capitis, named for the appearance of "black dots" of infected hairs broken just above the follicles, along with large patches of inflammation.


  • In all forms of tinea capitis, hair that is infected and broken may be permanently lost.

    Because tinea capitis may have features that also suggest seborrheic dermatitis or psoriasis, diagnosis must be confirmed by laboratory tests specific for fungal infection. After diagnosis is confirmed, treatment may include an oral anti-fungal drug such as terbinafine, griseofulvin or ketoconazole and a steroid to reduce inflammation. Many organisms are moderately resistant to griseofulvin and ketoconazole, which are also difficult to use long-term. Thus, terbinafine is most commonly given orally for 2 to 4 weeks to eradicate the infection. Oral medications are required because topical creams cannot reach the base of the hair follicle deep within the scalp where infection may be present.



    Bacterial and Viral Infections of the Scalp

    Various types of bacteria, some that live normally and harmlessly on the skin, can become invasive and cause infection. Staphylococci ("staph") are frequent offenders; when they infect the scalp the result is often folliculitis (inflammation of hair follicles), with or without abscess formation. Skin is inflamed and painful around the infected follicles. Persistent folliculitis can lead to permanent hair loss. Treatment with antibiotics is usually necessary.

    Viral scalp infection may be due to herpes simplex (the "cold sore" virus) or herpes zoster (the "shingles" virus). Symptoms may include folliculitis. Herpes zoster infection produces inflamed and extremely painful lesions on the skin-a classic symptom of shingles. Anti-viral medication may be prescribed after appropriate diagnosis.



    Head Lice

    Pediculosis capitis, the head louse, is one of humanity's constant-and unwelcome-companions. It has become adapted to a narrow environmental niche-living as a parasite on the human scalp. Related forms of louse have adapted to living as parasites on the body (body louse) or on the pubic area (crab louse).

    The bite of a louse is usually undetectable, but the site of the bite becomes inflamed and itchy. The most common first symptom of infestation with head lice is intense itching. Examination of the scalp will reveal red, swollen patches in the itchy areas. Examination of the hair typically reveals clusters of grayish-white louse eggs (nits) attached to the hair shafts. Further examination will usually find live adult lice.

    Outbreaks of head louse infestation are most likely at sites such as schools, nursing homes and military barracks where people come into close contact. A head louse infestation does not necessarily indicate that the infested person is "dirty", although this is a common belief. An infestation simply indicates that a person came into a situation where transfer of lice or louse eggs could easily occur.

    Once a head louse infestation has been discovered, all members of the household or community (nursing home, barracks) should be examined. Consideration may be given to treating the entire household or community with anti-louse medication. All clothing should be thoroughly washed in very hot water, or dry cleaned. All combs and brushes should be cleaned and washed in anti-louse medication. Over-the-counter anti-louse medications are available and may be adequate to bring a single infestation under control when properly used. More potent oral and topical anti-louse medications are available only by prescription.



    Psoriasis of the Scalp

    Psoriasis is an inflammatory, systemic skin disease characterized by red, scaly lesions that may involve portions of the body or nearly the entire body. A genetic predisposition is indicated by the number of psoriatic patients who have relatives with psoriasis. While the underlying cause of psoriasis is still unknown, considerable evidence points to dysfunction of the immune system as a cause or contributing factor.

    While psoriatic lesions can appear anywhere on the body, the scalp is one of the most frequent sites. The scalp may be the first site affected in children and young adults, and in some persons it remains the only site affected.

    Psoriasis has many levels of severity and many different clinical features ranging from shedding of grayish scales to pustular eruptions. Severe forms of psoriasis may be associated with other inflammatory conditions, especially psoriatic arthritis and inflammatory bowel disease (see What is Inflammation?).

    Psoriasis of the scalp usually has a distinctive appearance of inflamed skin overlain with silvery scales. In severely progressive disease the psoriatic lesions may merge into a solid mass of scales over the entire scalp, with temporary or permanent hair loss. Psoriasis of the scalp and seborrheic dermatitis of the scalp have many features in common and may be confused unless properly diagnosed. Atopic dermatitis, an inflammatory, extremely pruritic skin disease, may also resemble psoriasis; scalp involvement in atopic dermatitis is more frequent in infants and children but does occur also in adults. Because treatment is different for each of these diseases, correct diagnosis is essential to appropriate treatment.

    Authoritative information about psoriasis and specifically psoriasis of the scalp is available at:

    http://www.skincarephysicians.com/psoriasisnet/index.html

    http://www.psoriasis.org/about/psoriasis/scalp/

    http://www.psoriasisguide.com



    Diseases of Autoimmune or Unknown Origin Affecting the Scalp

    A person with an inflammatory autoimmune disease is probably aware of the condition and is under treatment. Scalp involvement is not likely to be the first manifestation; however, involvement of the scalp may occur in the course of the disease and become a significant problem for the patient. Lichen planus and lupus erythematosus are two such diseases that may involve the scalp. Alopecia areata is a disease of presumably autoimmune origin that causes hair loss.

    Lichen Planus

    Lichens are mossy-appearing plants that grow flat along the surfaces of rocks. The disease lichen planus draws its name from the appearance of characteristic lesions-lichen-like, furrowed scales and papules on skin, mucous membranes, fingernails and toenails, and across hair follicles on the scalp.

    The cause of lichen planus is unknown, but genetic factors and dysfunction of the immune system appear to be involved. Some investigators suggest that a predisposition to the disease may be triggered by infection or exposure to an environmental agent. Once triggered, an immune system dysfunction may cause the immune system to launch an attack on "self", the body's own cells-a failure of self-recognition by the immune response is called autoimmunity.

    The form of lichen planus involving hair follicles is called follicular lichen planus or planopilaris. Damage to hair follicles can cause scalp scarring and permanent hair loss. End-stage lichen planus of the scalp is characterized by complete hair loss and extensive scalp scarring

    Lupus Erythematosus

    Lupus erythematosus is also a disease of unknown, but probably autoimmune origin. Systemic lupus erythematosus (SLE) involves multiple organs and is progressively disabling. Discoid lupus erythematosus (DLE) is a form that involves only the skin; characteristic features are patchy skin inflammation, scaling of the skin, plugging of hair follicles, telangiectasia (rupture of small blood vessels just under the surface of the skin) and excessive skin dryness. DLE can result in scalp scarring and permanent hair loss. Neither form of lupus erythematous can be self-treated; all lupus patients should be under the care of a dermatologist or other physician with knowledge and experience of lupus symptoms and treatment.

    Alopecia Areata

    Alopecia areata is the most common cause of hair loss other than androgenetic alopecia (male- and female-pattern hair loss). Its cause is unknown, but autoimmunity has been suggested on the basis of research. Find more discussion of alopecia areata at (see Genes, Hair Growth and Hair Loss).



    Acne of the Scalp

    While acne is most often an eruption on the faces of adolescents and young adults, severe forms that cause deep scarring can involve the scalp. Scalp involvement can occur at any age from adolescence to age 50 or older.

    The cause of acne is not known with precision, but acne is commonly associated with seborrhea (see Seborrhea of the Scalp) and excessively oily skin. The severe forms of acne that may affect the scalp should be treated by a dermatologist. Severe acne lesions on the scalp may destroy hair follicles and result in patchy hair loss.

    Authoritative information about the causes and treatment of acne is available at a Website of the American Academy of Dermatology: http://skincarephysicians.com/acnenet/



    Allergic and Irritant Contact Dermatitis of the Scalp

    Allergic and irritant contact dermatitis is experienced by millions of people every year. Contact dermatitis is characterized as an inflammatory, often pruritic (Itchy) condition caused by reaction of the skin after contact with a sensitizing external agent. The classic example is the itchy and blistered skin that follows contact with poison ivy. Other agents causing allergic and irritant contact dermatitis range from household products such as soaps and detergents, to personal-care products such as cosmetics and perfumes, to work-place chemicals.

    Irritant contact dermatitis usually appears immediately or soon after contact with an irritant agent. Allergic contact dermatitis characteristically appears upon encountering an agent that previously came into contact with the skin; an allergic response usually requires sensitization by an initial encounter with the allergenic agent.

    Hair dyes or ingredients of hair-care products such as hair straighteners, permanent wave solutions, hair tonics, etc., are the external agents most frequently responsible for allergic or irritant contact dermatitis of the scalp. While major manufacturers strive to eliminate any irritating or allergic potential from their hair-care products, some individuals may have skin characteristics that predispose them to inflammatory or allergic reactions to certain sensitizing agents. "Home-made" products such as lye-based hair straighteners are not safety tested and can have significant potential for causing contact dermatitis. Irritant contact dermatitis is characterized by inflammation and burning sensations soon after contact with an irritant agent. Severe, persistent inflammation may result in temporary or permanent hair loss. The condition usually resolves over time, after withdrawal of the irritant. Persistent dermatitis should be treated by a physician.

    Allergic contact dermatitis can have varying presentations ranging from mild scalp inflammation to chronic eczema and involvement beyond the scalp to inflammation and edematous swelling of the face and neck. Unlike irritant contact dermatitis, allergic contact dermatitis can persist for days to weeks after withdrawal of the allergenic agent. Persistent allergic contact dermatitis requires medical treatment.



    Bibliography


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  • Eisenberg EL. Hair loss unrelated to androgenetic alopecia. In: Unger WP, Shapiro R (eds): Hair Transplantation, 4th ed. New York: Marcel Dekker, Inc.; 2004:67-79.