regresses at puberty. Localized hypertrichosis Congenital localized hypertrichosis is a localized increase in hair density and length. Nevoid hypertrichosis Nevoid hypertrichosis may be present at birth or appear later in life. It features an isolated area of excessive terminal hair and is usually not related to any other diseases. Acquired 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 lanuginosa Acquired hypertrichosis lanuginosa is characterized by rapid growth of lanugo hair, particularly on the face. Hair also appears on the trunk and armpits, while palms and soles are unaffected. The excess hair is commonly referred to as malignant down. This hair is very fine and unpigmented. Generalized hypertrichosis Acquired generalized hypertrichosis commonly affects the cheeks, upper lip, and chin. This form also affects the forearms and legs, but is less common in these areas. Another deformity associated with acquired generalized hypertrichosis is multiple hairs occupying the same follicle. It may also include abnormal hair growth patterns as what happens to the eyelashes in a condition known as trichiasis. Oral minoxidil treatments for hypertension are known to cause this condition. Topical minoxidil used for alopecia causes hair growth in the areas where it is applied; however, this hair disappears shortly after discontinuing the use of topical minoxidil. Patterned hypertrichosis Acquired patterned hypertrichosis is an increase in hair growth in a pattern formation. It is similar to acquired generalized hypertrichosis and is a sign of internal malignancy. Localized hypertrichosis Acquired localized hypertrichosis is an increase in hair density and length often secondary to irritation or trauma. This form is restricted to certain areas of the body. Hirsutism 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