Androgenetic alopecia (AGA) is often perceived as an indication of diminished physical attractiveness, particularly in Western societies. Disorders such as extensive alopecia areata and folliculitis decalvans are causes of hair loss that may lead to profound psychological problems. Other types of alopecia may be due to temporary disease or medication reactions (e.g., cytotoxic drugs, birth control pills, anticoagulants).

AGA in men and women (patterned alopecia), diffuse alopecia, occurring mainly in white women, and traumatic alopecia in women of African descent are the most common causes of hair loss in adults. Alopecia areata and tinea capitis account for most cases of alopecia in children.

For diagnostic purposes, it is helpful to recognize the pattern and distribution of hair loss. Whether patterned, as in male and female AGA; diffuse, as in telogen effluvium; focal, as in occipital alopecia of the newborn and most instances of alopecia areata; or patchy, as in tinea capitis, such findings afford important clues to its etiology.

Scarring alopecia, a permanent loss of hair follicles, also known as cicatricial alopecia, comprises a diverse group of disorders that may be due to infections, trauma (often self-induced), discoid lupus erythematosus, or lichen planopilaris. Scarring alopecia is seen in all ethnic groups and races; however, women and men of African descent are most often affected.



Androgenetic Alopecia

Distinguishing Features

  • Males: M-shaped pattern, which subsequently may involve the vertex (Fig. 1-1)

  • Females: Christmas tree pattern (widening of the part) on crown of scalp; more subtle, and tends to begin later in life than in males (Fig. 1-2)

  • Frontal hairline margin is typically spared (Fig. 1-3)

Diffuse Alopecia

Acute Telogen Effluvium

Distinguishing Features

  • Diffuse, nonpatterned alopecia due to loss of resting (telogen) hairs

  • Usually without obvious completely bald patches (Fig. 1-5)

Chronic Telogen Effluvium

  • This diffuse, nonpatterned type of hair loss, an ongoing progression of alopecia, is likely to involve the entire scalp

  • Initially, it tends to be subtle and is often not obvious to the clinician; however, the patient reports recurrent periods of increased shedding

  • There is no scarring or inflammation and hair thinning ultimately manifests as a more visible scalp

Anagen Effluvium

Senescent Alopecia


Occipital Alopecia of the Newborn (Telogen Effluvium of the Newborn)

Telogen Effluvium in Infants and Children

Distinguishing Features

  • A subtle hair shedding and generalized thinning throughout the scalp occurs 2 to 4 months after the triggering event

  • Young children rarely notice a change in hair density

  • Affected adolescents and parents of young children may report an increased shedding as noted by an increased number of hairs on a brush or comb, on pillows or clothing

  • Clinical spectrum is variable and may go unnoticed

Alopecia Areata

Jan 8, 2023 | Posted by in Dermatology | Comments Off on Hair
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