What is Hypertrichosis?
Hypertrichosis refers to excessive hair growth in any part of the body, whether in males or females. This condition differs from hirsutism – a term specifically used to describe women who grow too much coarse, thicker hair in areas typically associated with men because of male sex hormones.
Hypertrichosis can be classified in several ways, based on its spread over the body (widespread vs. localized), when it starts (at birth or later in life – congenital vs. acquired), and the type of hair involved (fine, short hair called vellus, or thick, coarse hair called terminal).
Examples of widespread hypertrichosis include congenital generalized hypertrichosis (which is further divided into different types), pre-adolescent hypertrichosis, acquired generalized hypertrichosis, etc. Each type varies in causes and symptoms.
Localized hypertrichosis can also take different forms. It includes congenital localized hypertrichosis (birthmarks, nerve tissue tumors, brownish skin overgrowth, localized excessive hair growth, spinal dysraphism which is a congenital disorder, and hair collar sign), localized hypertrichosis in hereditary and acquired systemic disease, and acquired localized hypertrichosis.
Understanding the types of hair – lanugo, vellus, and terminal hair – is crucial when judging a patient with potential hypertrichosis. Lanugo is a fine, uncolored hair that cover babies in the womb. It’s often quite long but should be replaced by vellus hair on the body and terminal hair on the scalp within a few weeks of birth. Vellus hair, sometimes called ‘peach fuzz,’ is short, fine and lightly pigmented. It’s found on the face, arms, stomach, and legs. Terminal hair is thicker, coarser hair found on the scalp, underarms, and pubic area. In males, terminal hair is also found on the face. During puberty, under the influence of testosterone, vellus hair changes to terminal hair in certain areas.
What Causes Hypertrichosis?
Congenital generalized hypertrichosis is a characteristic of a few uncommon inherited conditions where genetic mistakes affect the proteins involved in hair growth. There’s some evidence that exposure to certain medications like minoxidil while in the womb could make a child more likely to have this condition.
Before puberty, some cases of hypertrichosis are connected to having high levels of free and total testosterone.
Hypertrichosis that develops later in life is often caused by medications. Some examples of these medications include antibiotics, anti-inflammatory drugs, vasodilators, diuretics, anticonvulsants, immunosuppressives, psoralens, antiseptic agents, chelators, Interferon-alpha, Fenoterol, and EGFR inhibitors. Although medications are usually the cause, hypertrichosis can also happen following traumatic brain injuries, underactive thyroid in children, certain muscle conditions, acromegaly, malnutrition, and advanced HIV infection.
Acquired hypertrichosis lanuginosa is often linked to cancer, and sometimes it can even develop before a cancer diagnosis. It’s most commonly seen in lung, colon, and breast cancers. Sometimes, it occurs with other skin changes that are linked to cancer, such as thick dark patches on the skin, thickening of the skin on the palms and soles, LESER-TRELAT sign, and ichthyosis.
Several forms of localized hypertrichosis, such as hairy elbow syndrome, hairy palms and soles, hypertrichosis of the ear, hypertrichosis of the nose tip, and hypertrichosis of the neck are inherited. Excessively long eyelashes, on the other hand, occur because of a different, recessive pattern of inheritance.
Certain birthmarks are often associated with excess hair growth that becomes apparent during infancy. Plexiform neurofibromas, which are characteristic of neurofibromatosis type I, also have associated hypertrichosis.
Nevoid hypertrichosis causes can vary. Primary nevoid hypertrichosis happens without any other associated conditions. However, secondary nevoid hypertrichosis can be associated with conditions such as fat loss, uneven growth, scoliosis, and abnormalities of the underlying blood vessels.
Some inherited and acquired systemic diseases can also cause localized hypertrichosis. Examples include Cornelia de Lange syndrome and Rubinstein-Taybi syndrome. Porphyria cutanea tarda can cause hypertrichosis in sun-exposed areas. Certain syndromes like Berardinelli-Seip syndrome caused by gene mutations can present with hypertrichosis as well.
Acquired localized hypertrichosis can be caused by repeated trauma, friction, irritation, or inflammation. It’s often observed on the backs of people who carry heavy loads, over a broken limb after being put in a cast, and over the neck in weightlifters. It can also be seen within vaccination sites and from chicken pox scars. Hypertrichosis has been reported at sites of wart removal and laser hair removal. Acquired localized hypertrichosis can also be the result of medical intervention; it has been described following certain therapies, topical corticosteroids, tacrolimus, creams containing mercury or iodine, anthralin, and prostaglandin F-2 alpha analogs.
Risk Factors and Frequency for Hypertrichosis
Hypertrichosis, a condition marked by excessive hair growth, typically affects both men and women equally. However, certain forms of this condition may be more common in different groups. For instance, young children from Mediterranean or South Asian backgrounds often experience prepubertal hypertrichosis. In addition, specific types of inherited hypertrichosis, like hypertrichosis of the auricle (ear) and the nasal tip, are primarily seen in males.
Signs and Symptoms of Hypertrichosis
Hypertrichosis is a condition marked by excessive hair growth on the body. The symptoms vary depending on the type of hypertrichosis a person has:
- In generalized hypertrichosis, individuals have lanugo (fine, soft, and usually unpigmented), vellus, or terminal hair (long, coarse, pigmented) covering most of their body. In some cases, terminal hair can change to lanugo hair.
- In congenital hypertrichosis lanuginosa, people have fine, silver-gray to blond lanugo hair covering their entire body except the palms, soles, hands, feet, and prepuce. Their hair can grow up to 10 centimeters long, giving them a “werewolf” appearance. This form of hypertrichosis may also come with dental abnormalities, glaucoma, pyloric stenosis, and sensitivity to light.
- Universal hypertrichosis, another form of congenital generalized hypertrichosis, causes thick, long hair on the back, on parts close to the body, and around the ears. This condition is commonly referred to as “exaggerated normal hairiness.”
- Hypertrichosis universalis congenita or Ambras syndrome presents with light-colored long hair primarily around the face, ears, shoulders, and nose. Alongside the excessive hair, those with this syndrome may exhibit facial differences, extra nipples, and dental anomalies.
- Prepubertal hypertrichosis typically presents during childhood with diffuse hair growth over the face, proximal extremities, and back, often in an “inverted fir tree” pattern. Thickened eyebrows and a low hairline are also characteristic.
- Acquired generalized hypertrichosis is characterized by the slow growth of terminal hairs on the forehead, temples, flexors, and trunk. The condition can be reversed and is often associated with systemic disease, certain medications, or traumatic brain injury.
- Acquired hypertrichosis lanuginosa is where fine lanugo hairs rapidly cover the entire body, although milder forms affecting just the face do exist. Patients with this condition may have a history of cancer.
There are also several forms of congenital localized hypertrichosis, which includes:
- Hairy elbow syndrome which presents with excessive hair over the forearms and elbows.
- Hairy palms and soles syndrome.
- Hypertrichosis of the auricle, eyebrows, and nasal tip.
- Anterior cervical hypertrichosis and Posterior cervical hypertrichosis.
Becker melanosis presents as a patch of irregular, darkly pigmented skin on the upper trunk, and excessive hair growth in the affected area usually follows during the second decade of life. Nevoid hypertrichosis presents as a well-defined area of excessive terminal hair growth. Localized areas of hypertrichosis may indicate underlying defects in the area beneath the excessive hair growth. Porphyrias like porphyria cutanea tarda (PCT) and hepatoerythropoietic porphyria can cause excessive hair growth in sun-exposed areas. Acquired localized hypertrichosis can manifest as an overgrowth of hair, increased skin pigmentation, and thickening of the skin at the site of repeated friction or trauma.
Testing for Hypertrichosis
If you visit a doctor due to excessive hair growth, or hypertrichosis, the first step the doctor will take is to determine whether you were born with it (congenital) or developed it over time (acquired). This can usually be understood from your health history.
If the doctor thinks that the excessive hair growth is present from birth, they will then determine if the hair is fine and lightly colored (lanugo hairs) or if it is pigmented, similar to the mature hair we usually have (terminal hairs). If more mature hair is present, the doctor will consider your family’s hair history, whether your mother took any drugs or alcohol during her pregnancy, and whether there are any unusual characteristics related to your face, skeleton, eyes, or nervous system. These could suggest a rare genetic condition related to hair growth.
On the other hand, if the doctor believes your excess hair growth developed over time, they will again check whether the hair is mature or light-colored. If there is more mature hair and you have slowly developed hypertrichosis, the doctor will then check for signs of hair growth often seen in children before puberty, especially if you are of Mediterranean or South Asian descent. They will also check for signs or symptoms of excessive male hormones such as early development of armpit or pubic hair, masculine characteristics, acne, and increased levels of male hormones. This may suggest that you have hirsutism, which is different from hypertrichosis. If more mature hair corresponds to a rapid influx of hair growth, the doctor will consider your nutrition and your levels of thyroid hormone and will look into any medication you might be taking. In case, you suddenly appear to have light-coloured hair, the doctor will check for signs of cancer, as this can be an indication of it.
Treatment Options for Hypertrichosis
Laser hair removal, hair removal creams, and a process called electrolysis can all be used to get rid of unwanted hair. The best types of lasers for hair removal include the Nd:Yag laser, Alexandrite laser, and diode laser. Hair removal creams usually contain ingredients like calcium thioglycolate and barium sulfate. These creams can effectively remove hair, but they may cause skin irritation in some cases.
What else can Hypertrichosis be?
When doctors are trying to figure out if someone has hypertrichosis, which is excessive hair growth, they will also consider another condition called hirsutism. Both men and women can show signs of hypertrichosis, but the term “hirsutism” is specifically used when women experience hair growth in areas usually seen in men. Hirsutism is typically caused by higher levels of male hormones, known as androgens, and is often linked with other signs or symptoms that suggest a surplus of androgens.
What to expect with Hypertrichosis
The future outlook of hypertrichosis, which is excessive hair growth, varies greatly and depends on the specific type a person has. If hypertrichosis is associated with certain genetic syndromes, it’s generally a lifelong condition. On the other hand, if a medication causes hypertrichosis, stopping that medication usually reverses the excessive hair growth.
Preventing Hypertrichosis
If hypertrichosis is present due to genetic factors, it’s important for patients to understand that their children might also inherit this condition. Hypertrichosis is an excessive hair growth condition.
