Hypertrichosis

Hypertrichosis (sometimes known as werewolf syndrome) is an abnormal amount of hair growth over the body. The two distinct types of hypertrichosis are generalized hypertrichosis, which occurs over the entire body, and localized hypertrichosis, which is restricted to a certain area. Hypertrichosis can be either congenital (present at birth) or acquired later in life. The excess growth of hair occurs in areas of the skin with the exception of androgen-dependent hair of the pubic area, face, and axillary regions.

Several circus sideshow performers in the 19th and early 20th centuries, such as Julia Pastrana, had hypertrichosis. Many of them worked as freaks and were promoted as having distinct human and animal traits.

Two methods of classification are used for hypertrichosis. One divides them into either generalized versus localized hypertrichosis, while the other divides them into congenital versus acquired.

Congenital forms of hypertrichosis are caused by genetic mutations, and are extremely rare, unlike acquired forms. Congenital hypertrichosis is always present at birth.

Acquired hypertrichosis appears after birth. The multiple causes include the side effects of drugs, associations with cancer, and possible links with eating disorders. Acquired forms can usually be reduced with various treatments.

Hypertrichosis is often mistakenly classified as hirsutism. Hirsutism is a type of hypertrichosis exclusive to women and children, resulting from an excess of androgen-sensitive hair growth. Patients with hirsutism exhibit patterns of adult male hair growth. Chest and back hair are often present on women with hirsutism.

Hirsutism is both congenital and acquired. It is linked to excessive male hormones in women, thus symptoms may include acne, deepening of the voice, irregular menstrual periods, and the formation of a more masculine body shape. Increases in androgen (male hormone) levels are the primary cause of most hirsutism cases. If caused by increased levels of androgens, it can be treated with medications that reduce androgen levels. Some birth control pills and spironolactone reduce androgen levels.

The primary characteristic of all forms of hypertrichosis is excessive hair. Hair in hypertrichosis is usually longer than expected and may consist of any hair type (lanugo, vellus, or terminal). Patterned forms of hypertrichosis cause hair growth in patterns. Generalized forms of hypertrichosis result in hair growth over the entire body. Circumscribed and localized forms lead to hair growth restricted to a certain area.^{[citation needed]}