Hypertrichosis and Hirsutism

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Hypertrichosis and Hirsutism

Definitions

• Hypertrichosis: excessive hair growth on any area of the body, beyond what is normally expected for a patient’s demographic group.

• Hirsutism: excessive terminal hair growth in women or children in a pattern typically seen in adult men.

• Lanugo hair: long fine hair that is grown in utero, covers the fetus, and is normally shed either in utero or during the first few weeks of life.

• Vellus hair: short, non- or lightly pigmented hair that covers most areas of the body; occasionally so fine as to not be appreciated clinically.

• Terminal hair: thick pigmented hair that is typical of the scalp and androgen-dependent areas, such as the axillae and pubic region in both sexes, as well as the beard, trunk, and limbs in adult males.

• Hyperandrogenism: elevated serum levels of testosterone, DHEAS, and/or androstenedione; cutaneous findings include hirsutism, severe or treatment-resistant acne, androgenetic alopecia, and seborrhea.

• Virilization: in women, clinical features of hyperandrogenism plus clitoromegaly, deepened voice, increased muscle mass, breast atrophy, and increased libido.

• Depilation: removal of a portion of the hair at some point along its shaft.

• Epilation: removal of the entire hair shaft.

Hypertrichosis

• Can be classified based on the distribution (generalized vs. localized), age of onset (congenital or early onset vs. acquired), and type of hair (lanugo vs. vellus vs. terminal).

• Three mechanisms of hypertrichosis are generally recognized:

1. Conversion of vellus to terminal hair (e.g. localized hypertrichosis in an area of chronic rubbing or scratching).

2. Changes in the hair growth cycle (e.g. intranasal and ear hairs in older males due to prolongation of anagen phase).

3. Increase in hair follicle density beyond what is normal for a given site (e.g. congenital melanocytic nevus).

• Rx: treat underlying condition, if possible, otherwise see Table 57.2.

• Shaving of hairs does not increase the thickness or pigmentation of the hairs, contrary to common belief.

Generalized Hypertrichosis

• The presence of lanugo hair, excess vellus hair, or terminal hair on most of the body.

• An approach to a patient with generalized hypertrichosis is presented in Fig. 57.1.

Fig. 57.1 Approach to the patient with generalized hypertrichosis. Acquired hypertrichosis lanuginosa occasionally may involve only the face.

• In young girls, constitutional prepubertal hypertrichosis is the most common form of generalized hypertrichosis.

Localized Hypertrichosis

• Most often involves a switch from vellus to terminal hair in sites that normally do not have terminal hairs.

• Congenital localized hypertrichosis is usually related to an underlying hamartoma or occurs at a specific anatomic site (Table 57.1; Figs. 57.2–57.6).

Table 57.1

Classification and key features of selected disorders of localized hypertrichosis.

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