Alopecia

Key Features

Essentials of Diagnosis

Forms of hair loss

• Scarring (suggested by absent follicular markings)

• Nonscarring (suggested by present follicular markings)

General Considerations

Scarring

• Irreversible and permanent, thus it is important to treat the scarring process as early as possible

• May occur following

  • Chemical or physical trauma

  • Bacterial or fungal infections

  • Severe herpes zoster

  • Chronic discoid lupus erythematosus

  • Scleroderma

  • Excessive ionizing radiation

• Specific dermatologic diseases of the scalp that result in scarring alopecia include

  • Lichen planopilaris

  • Frontal fibrosing alopecia

  • Dissecting cellulitis of the scalp

  • Folliculitis decalvans

• The specific cause is often suggested by

  • The history

  • The distribution of hair loss

  • The appearance of the skin, as in lupus erythematosus

Nonscarring

• May occur in association with various systemic diseases such as

  • Systemic lupus erythematosus

  • Secondary syphilis

  • Hyperthyroidism or hypothyroidism

  • Iron deficiency anemia

  • Vitamin D deficiency

  • Pituitary insufficiency

Androgenetic alopecia

• Both men and women are affected, often starting in the third decade

Telogen effluvium

• A transitory increase in the number of hairs in the telogen (resting) phase of the hair growth cycle

• Causes

  • Spontaneous occurrence

  • Iron deficiency

  • May appear at the termination of pregnancy

  • Precipitated by "crash dieting," high fever, stress from surgery or shock, or malnutrition

  • Provoked by hormonal contraceptives

• Latent period of 2–4 months

• The prognosis is generally good

Alopecia areata

• Unknown cause but is believed to be an immunologic process (autoimmune)

• Occasionally associated with Hashimoto thyroiditis, pernicious anemia, Addison disease, and vitiligo

Clinical Findings

Symptoms and Signs

Androgenetic alopecia

• In men, the earliest changes occur at the anterior portions of the calvarium on either side of the "widow's peak" and on the crown (vertex)

• In women, there is retention of the anterior hairline while there is diffuse thinning of the vertex scalp hair and a widening of the part

• The extent of hair loss is variable and unpredictable

Alopecia areata

• Typically, there are patches that are perfectly smooth and without scarring

• Tiny hairs 2–3 mm in length, called "exclamation hairs," may be seen

• Telogen hairs are easily dislodged from the periphery of active lesions

• The beard, brows, and lashes may be involved

• Involvement may extend to all of the scalp hair (alopecia totalis) or to all scalp and body hair (alopecia universalis)

Differential Diagnosis

• Scarring (cicatricial)

  • Chemical or physical trauma

  • Lichen planopilaris

  • Bacterial or fungal infection

  • Herpes zoster (shingles) (severe)

  • Discoid lupus erythematosus

  • Scleroderma

  • Excessive ionizing radiation

• Nonscarring

  • Androgenic (male pattern) ...