There seems to be some confusion about the distinction between hypertrichosis and hirsutism. Hypertrichosis is hair growth over and above what is normally expected when comparing the individual to others of similar age and sex. The excess hair growth may or may not involve pigmented hair fiber. Hypertrichosis can develop all over the body or, more likely, it just develops in a small patch. Any hair bearing area of skin can be affected by hypertrichosis.
Hirsutism is excess terminal hair growth in women with a male distribution pattern.
The excess hair growth is limited to one or more areas including the mustache, beard, chest, and genital region. Hirsutism is usually associated with increased or reduced exposure to hormones. Primary causes of hypertrichosis are listed and briefly explained below. The hair growth can be excessive for a wide variety of reasons and may involve the entire body with a mass of fine long hair, diffuse excess hair, or may be restricted to specific areas. Causes of congenital hypertrichosis vary.