Alopecia

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How is alopecia classified?

Alopecia (hair loss) can be divided into (1) disorders of the hair shaft and (2) all other forms of hair loss. Abnormalities of the hair shaft can produce alopecia because the shafts are fragile and “break off.” The other forms of alopecia can be divided into cicatricial (scarring) and noncicatricial alopecia. In cicatricial alopecia, hair is lost permanently. In noncicatricial alopecia, hair follicles may return to growth either spontaneously or with treatment. Both cicatricial and noncicatricial alopecia can be divided into diffuse and patterned hair loss. In diffuse hair loss, hair thins evenly from all parts of the scalp, and discrete “bald spots” do not occur. In patterned alopecia, certain areas of the scalp are affected more than others.

Eudy G, Solomon AR. The histopathology of noncicatricial alopecia. Semin Cutan Med Surg. 2006;25:35–40.

Sperling LC, Cowper SE. The histopathology of primary cicatricial alopecia. Semin Cutan Med Surg. 2006;25:41–50.

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What are some common types of patterned hair loss?

• Patchy: Multiple scattered lesions

• Moth-eaten: Myriad, diffusely distributed, small lesions

• Ophiasis: Hair loss around periphery of the scalp

• Male pattern alopecia: Symmetrical, progressive hair loss predominantly affecting the top (vertex) of the scalp possibly leading to complete baldness

• Female pattern alopecia: Partial hair loss on the frontal and vertex of the scalp with reduction of hairs, not leading to complete baldness

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Can cicatricial and noncicatricial alopecia be differentiated clinically?

In the setting of alopecia, cicatricial means that there has been permanent destruction of hair follicles, and they have been replaced by fibrous tissue. Usually, an obvious scar, such as that seen after wounding, is not evident, but there is a loss of follicular openings that gives the scalp a smooth and shiny appearance ( Fig. 20.1 ). The texture of the scalp may remain soft and supple, although sometimes induration or firmness is palpable.

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What causes common hair loss?

People who become bald or develop thinning hair have hair follicles that are genetically programmed to miniaturize under the influence of postpubertal androgens. Probably, several genes (inherited from both mother and father) influence the severity of balding. Until very late in the balding process, the number of hairs does not decrease, but the hairs become progressively smaller until they are no longer visible to the naked eye. Except in very marked and long-standing balding, very fine, short hairs can be seen exiting from follicular orifices if a magnifying lens is used.

Randall VA. Androgens and hair growth. Dermatol Ther. 2008;21(5):314–328.

Yip L, Rufaut N, Sinclair R. Role of genetics and sex steroid hormones in male androgenetic alopecia and female pattern hair loss: an update of what we now know. Australas J Dermatol . 2011;52(2):81–88.

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How effective are medical treatments for common hair loss?

About one-third of balding patients who use topical minoxidil solution experience significant (cosmetically obvious) hair regrowth. Any regrowth that occurs is only maintained while the drug is used. If therapy is stopped, hair density reverts to its pretreatment state. Oral finasteride, a 5α-reductase inhibitor, is somewhat more effective and can be used in combination with topical minoxidil in men and postmenopausal women. Other antiandrogen oral medications can also be used in refractory cases.

Rousso DE, Kim SW. A review of medical and surgical treatment options for androgenetic alopecia. JAMA Facial Plast Surg. 2014;16(6):444–450.

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Is common hair loss in women managed differently than in men?

Women whose hair loss is a manifestation of hyperandrogenism (excessive production of circulating androgens) may benefit from therapy directed at the cause of the hyperandrogenism. Polycystic ovarian syndrome, late-onset congenital adrenal hyperplasia, Cushing's syndrome, and adrenal and ovarian neoplasms are potential causes of hyperandrogenism. In the absence of elevated circulating androgens, nonspecific therapy directed at suppressing ovarian androgen production or blocking the peripheral effect of androgens can be effective. Oral contraceptive agents (to suppress ovarian androgen production) and spironolactone are most often utilized for this purpose. Topical minoxidil solution is also useful, but oral finasteride is seldom used in women unless postmenopausal.

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