Table 1.
Noncicatricial alopecias |
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Androgenetic alopecia |
Most common type of hair loss in both men and women Onset may be as early as puberty: 50% of men affected by age 50, 40% of women by age 70 Male pattern: Thinning of the frontal hairline, bitemporal recession, hair loss at the crown Female pattern: Hair loss at the crown with preservation of the frontal hairline Caused by the effect of dihydrotestosterone on hair follicles leading to miniaturization |
Alopecia areata |
Equally affects both sexes, with usual onset before age 30 Most common areas of hair loss are scalp and beard regions Round areas of complete hair loss with retained follicular ostia Exclamation point hairs found at the edges of expanding areas of hair loss are a hallmark sign Caused by autoimmune destruction of hair follicles involving cell-based and humoral immunity |
Telogen effluvium |
Acute telogen effluvium is characterized by diffuse scalp hair loss lasting <6 mo, whereas the duration is >6 mo for chronic telogen effluvium Women between ages 30 to 60 are most commonly affected A stressor event may or may not be present, usually occurring 2–4 mo before onset of hair shedding 20%–50% of scalp hairs transition prematurely to telogen phase and are shed with normal hair shafts |
Anagen effluvium |
Diffuse hair loss characterized by hair breakage during anagen phase Classic causative agents are radiation therapy and cancer chemotherapy Affects 80%–90% of scalp hairs with onset within 1–4 wk of exposure Narrowing, fractured hair shafts constitute a characteristic sign |
Loose anagen syndrome |
Typical patient is a blond female aged 2–5 who presents with diffuse hair loss and short, dull hair 6:1 Female to male ratio among the patient population, which includes adults and dark-haired individuals as well Greater susceptibility to hair breakage caused by premature keratinization of the inner root sheath, causing impaired adhesion with the hair shaft cuticle Shorter anagen phase leads to reduced hair length |
Trichotillomania |
Patients experience an irresistible urge to pull out their own hair despite negative impacts to their occupational and social function Childhood trichotillomania affects more boys than girls and resolves spontaneously Adult trichotillomania affects women much more frequently than men Often comorbid with mood or anxiety disorders Short, fractured hairs distributed sparsely and irregularly in affected areas |
Traction alopecia |
Results from tension applied to hair for a prolonged period of time, from hairstyles such as tight ponytails and braids, as well as hair-styling devices Areas under greatest pressure are most affected, usually scalp margins Especially common among African-American females because of their association with certain hairstyles Typically hair loss is transient; scarring or inflammation may be observed |
Cicatricial alopecias |
Chronic cutaneous lupus erythematosus |
Scaly, erythematous plaques with well-demarcated borders that eventually atrophy, found on sun-exposed areas including scalp Most common form is discoid lupus erythematosus, accounting for 50%–85% of all cases Affects more women than men, usually between ages 20–45 Associated with carpet tack sign, describing follicular spikes on the undersurface Cases among African-Americans are often more severe |
Lichen planopilaris |
Considered to be a variant form of lichen planus Classic lesions are smooth white areas with absent follicle ostia and central scarring; edges are characterized by erythema and scaling around hair follicles Mostly affects adult women at the crown and parietal areas of the scalp Due to autoimmune attack on hair follicles mediated by T lymphocytes |
Central centrifugal cicatricial alopecia |
Scarring hair loss that usually begins at the crown and expands outward to affect the entire scalp Middle-aged African-American females are most commonly affected; individuals of other races rarely present with this condition May be associated with chemicals and pressure applied to hair Lymphocyte-rich infiltrates observed at edges of balding lesions with signs of inflammation |