What is hypertrichosis

Hypertrichosis is defined as excessive hair growth anywhere on the body in either males or females, over and above the normal for the age, sex and race of an individual ¹. It is important to distinguish hypertrichosis from hirsutism, which is a term reserved for women who grow an excessive amount of terminal hairs in a male distribution pattern (androgen-dependent sites) ².

Hypertrichosis can cause severe emotional distress for patients, especially those who do not have access to permanent laser hair removal or electrolysis. Self-confidence and quality of life may be extremely low for these patients secondary to societal scrutinization and bullying in patients of all ages. In cases of severe hypertrichosis, it is imperative to arrange mental health care for patients in addition to medical care to address the underlying cause of the hypertrichosis, if there is one. The outcome of patients with hypertrichosis depends on the cause. For those with inherited disorders, there is no cure and poor cosmesis is a lifelong issue. For those with acquired hypertrichosis, the outcomes are good once the primary condition is treated or the offending medication discontinued.

There are several ways of classifying hypertrichosis. These are based on distribution, hypertrichosis can develop all over your body (generalized hypertrichosis) or can be isolated to small patches (localized hypertrichosis). The age of onset, hypertrichosis may be congenital hypertrichosis (present at birth) versus acquired hypertrichosis (arises later in life). And the type of hair (vellus versus terminal).

Acquired hypertrichosi describes excess hair growth that develops in an individual after birth. The hair is usually unpigmented vellus hair or may involve pigmented terminal hair. Excess hair growth may be localized to a particular area or generalized and covering all hair-bearing areas of the body.

Forms of generalized hypertrichosis include, but are not limited to, congenital generalized hypertrichosis (which is further divided into congenital hypertrichosis lanuginosa, universal hypertrichosis, and hypertrichosis universalis congenita), prepubertal hypertrichosis, acquired generalized hypertrichosis, and acquired hypertrichosis lanuginosa. They each differ in their cause and clinical findings ³.

Forms of localized hypertrichosis include, but are not limited to, congenital localized hypertrichosis (congenital nevi, plexiform neurofibromas, Becker melanosis/nevus, nevoid hypertrichosis, spinal dysraphism, and the hair collar sign), localized hypertrichosis in hereditary and acquired systemic disease, and acquired localized hypertrichosis ⁴.

An understanding of lanugo, vellus, and terminal hair is integral in evaluating a patient with presumed hypertrichosis. Lanugo hair is fine, non-pigmented hair that covers the normal fetus. It is often several centimeters long. By the first few weeks of life, lanugo hair should be replaced by vellus hair on the body and terminal hair on the scalp. Vellus hair is lightly pigmented, fine, short hair, often referred to as “peach fuzz” that is found on the face, arms, stomach, and legs. Terminal hair is coarse, thick hair that is found on the scalp, underarms, and pubic area. In men, terminal hair is also found on the face. During puberty, vellus hair is replaced with terminal hair in androgen-dependent sites under the influence of testosterone ².

Laser hair removal, depilatory creams, and electrolysis are used to remove unwanted hair. Laser hair removal appears to have fewer side effects and produces a longer lasting result.

Congenital hypertrichosis

Congenital generalized hypertrichosis is a feature of several rare inherited syndromes in which genetic errors result in dysfunction of proteins involved in the development of the hair follicle ⁵. There is some evidence to support that exposure to medications such as minoxidil in utero may predispose to congenital generalized hypertrichosis ⁶.

Several forms of congenital localized hypertrichosis including hypertrichosis cubiti (hairy elbow syndrome), hairy palms and soles, hypertrichosis of the auricle, hypertrichosis of the nasal tip, and anterior or posterior cervical hypertrichosis are inherited in an autosomal dominant fashion ⁷. Trichomegaly of the eyelashes is the exception, as it is an autosomal-recessive disorder ⁸.

Prepubertal hypertrichosis is linked to elevated levels of free and total testosterone in some patients ⁹. Prepubertal hypertrichosis is common in healthy, Mediterranean or South Asian infants and children ¹.

Congenital melanocytic nevi are often associated with hypertrichosis that becomes apparent during the infantile period or childhood. Plexiform neurofibromas, lesions pathognomonic for neurofibromatosis type 1, also have associated hypertrichosis ¹⁰.

Congenital hypertrichosis lanuginosa

Congenital hypertrichosis lanuginosa is a very rare syndrome with only about 50 cases reported worldwide since the Middle Ages ¹¹. Congenital hypertrichosis lanuginosa is characterized by excessive hair growth on a child at birth covering the entire body surface except the mucosae, palms, and soles. Most of the body is covered with lanugo hair, which is an unpigmented, fine, soft and silky hair that covers the fetus and which is usually shed at around 8 months gestation and replaced with fine vellus hair and terminal scalp hair in preparation for birth. In congenital hypertrichosis lanuginosa, lanugo hair continues to grow and this excessively long fine hair persists throughout life. Congenital hypertrichosis lanuginosa is considered to be an autosomal dominant disorder, but sporadic presentations are also reported ¹¹.

Figure 1. Congenital hypertrichosis lanuginosa

Footnote: A 15-month-old boy presented with a history of excessive hairiness since birth that increased progressively during infancy. At presentation, he had excess long, dark blond, silky hair on the face, ears, trunk, and limbs. There was accentuation of the hairiness over the lumbosacral spine and sacrum. His eyebrows were very thick and coarse, his eyelashes surprisingly long. The face was coarse, and there was a small sacral dimple. There were no indications of skeletal abnormalities. Findings of ophthalmologic and stomatologic examinations were normal. Extensive laboratory analyses, including endocrinologic and metabolic evaluations, revealed no abnormalities. His karyotype was normal. Family history revealed that his father had also been unusually hairy during infancy. The father experienced severe dental caries and wore complete dental prostheses by age 27 years. The father was observed to have coarse eyebrows and long eyelashes at the time of his son’s evaluation.

[Source ¹¹ ]

Congenital hypertrichosis terminalis

Congenital hypertrichosis terminalisis is also called werewolf syndrome, is a variation of congenital hypertrichosis. Congenital hypertrichosis terminalis involves all over body hair growth, but the hair is fully pigmented terminal hair and the condition is almost always associated with gingival hyperplasia (teeth defects). People with congenital hypertrichosis terminalis are often referred to as wolf men, werewolves and ape-men and back in the 19th century and perhaps even today, are crowd-drawers at sideshow acts.

Nevoid hypertrichosis

This is an unusual form of hypertrichosis where a solitary circumscribed area of terminal hair growth occurs. It is not usually associated with any other diseases, except if it arises as a faun-tail on the lower back, when it may indicate underlying spina bifida. Nevoid hypertrichosis can occur at birth or appear later in life. An example of nevoid circumscribed hypertrichosis is the presence of a solitary and very bushy eyebrow.

Nevoid hypertrichosis has a variable cause:

• Primary nevoid hypertrichosis occurs in the absence of extracutaneous associations.
• Secondary nevoid hypertrichosis is associated with lipodystrophy, hemihypertrophy, scoliosis, and abnormalities of the underlying vasculature ¹².

Hypertrichosis associated with other nevi

Hypertrichosis may also be a feature of congenital melanocytic nevus, vascular malformation, Becker nevus and less frequently, other birthmarks.

Hypertrichosis causes

The cause of hypertrichosis is unknown. Congenital hypertrichosis is believed to be a genetic disorder that is inherited or occurs as a result of spontaneous mutation. Acquired hypertrichosis lanuginosa sometimes occurs in people who at a later stage are diagnosed with a cancer of some form (paraneoplastic phenomenon) and in certain instances precedes the diagnosis of cancer ¹³. The most common malignancies that it is associated with include lung, colon, and breast cancers. It is sometimes seen in concert with other paraneoplastic dermatoses such as acanthosis nigricans, palmoplantar keratoderma, Leser-Trelat sign, and acquired ichthyosis. This hair growth, also known as malignant down, is often confined to the face with long fine silky hair noticeable on the nose and eyelids, sites that are normally hairless. It is not known why a cancer causes this excessive hair growth.

Generalized acquired hypertrichosis may be associated with:

• Porphyria cutanea tarda
• Malnutrition, e.g., anorexia nervosa
• Malignancy
• Drugs most often cause acquired generalized hypertrichosis:
  • Ciclosporin,
  • Androgenic steroids,
  • Antibiotics such as streptomycin,
  • Anti-inflammatory drugs such as benoxaprofen and corticosteroids,
  • Vasodilators (diazoxide, minoxidil, prostaglandin E1)
  • Diuretics (acetazolamide)
  • Anticonvulsants (phenytoin)
  • Immunosuppressives (cyclosporine, mycophenolate mofetil)
  • Psoralens (methoxypsoralen, trimethylpsoralen)
  • Antiseptic agents (hexachlorobenzene)
  • Chelators (penicillamine)
  • Interferon-alpha
  • Fenoterol
  • EGFR inhibitors (cetuximab, panitumumab, erlotinib, gefitinib)

Although drugs are usually the culprit, acquired generalized hypertrichosis can also be seen in traumatic brain injuries, juvenile hypothyroidism, juvenile dermatomyositis, acromegaly, malnutrition, and advanced HIV infection ¹⁴.

Localized acquired hypertrichosis may be associated with:

• Increased vascularity
• Repetitive rubbing or scratching (lichen simplex)
• Application of plaster cast (temporary)
• Repeated application of minoxidil, potent topical steroid, iodine, psoralens (topical PUVA)
• Trichomegaly (long eyelashes) can arise from local bimatoprost or systemic erlotinib.

There are several hereditary and acquired systemic diseases that present with localized hypertrichosis. Cornelia de Lange syndrome, caused by autosomal dominant or X-linked dominant mutations can present with synophrys (unibrow), as well as hypertrichosis over the forehead, lateral face, shoulders, and back ¹⁵. Rubinstein-Taybi syndrome is due to autosomal-dominant mutations and leads to hypertrichosis over the lateral face, shoulders, and back ¹⁶. Porphyria cutanea tarda is a cause of hypertrichosis in sun-exposed areas ¹⁷. Lipodystrophy syndromes, such as Berardinelli-Seip syndrome caused by AGPAT2, BSCL2, CAV1, CAVIN1/PTRF gene mutations, can present with hypertrichosis as well ¹⁸.

Acquired localized hypertrichosis is caused by repetitive trauma, friction, irritation or inflammation. For example, localized hypertrichosis is often observed on the back of sack carriers, over a fractured limb after plaster casting, and over the posterior neck in weightlifters. It can also be seen within vaccination sites and varicella scars ⁵. Hypertrichosis at sites of wart removal and laser epilation has also been reported in the literature. Acquired localized hypertrichosis can also be iatrogenic; it has been described following PUVA therapy, topical corticosteroids, tacrolimus, creams containing mercury or iodine, anthralin, and prostaglandin F-2 alpha analogues (latanoprost, bimatoprost) ¹⁹.

Hypertrichosis symptoms

Hypertrichosis symptoms differ between types of hypertrichosis. In generalized forms of hypertrichosis, the patient will present with lanugo hair, vellus hair, or terminal hair covering a majority of their body. Transformation of terminal hair to lanugo hair can be seen ²⁰.

There are several disorders characterized by congenital generalized hypertrichosis. Congenital hypertrichosis lanuginosa presents rather dramatically; the entire body surface, except for the palms, soles, dorsal hands and feet, and prepuce, is covered with fine, silver-gray to blond lanugo hair. Hair may grow up to 10 centimeters in length, giving a “werewolf” appearance. Congenital hypertrichosis lanuginosa may present with dental anomalies, glaucoma, pyloric stenosis, and photophobia ²¹.

Universal hypertrichosis, another form of congenital generalized hypertrichosis, presents with thick, long hair on the back, proximal extremities, and preauricular areas. It is often thought of “exaggerated normal hairiness” ²².

Hypertrichosis universalis congenita sometimes referred to as Ambras syndrome, presents with fine, silky, light-colored long hair primarily involving the face, ears, shoulders, and nose. It is associated with minor facial dysmorphism, supernumerary nipples, and dental anomalies ²³.

Patients with prepubertal hypertrichosis typically present with widespread, diffuse involvement that becomes obvious and bothersome during childhood. Hair growth favors the face (especially the forehead, temples, and preauricular area), proximal extremities, and back. It is described as having an “inverted fir tree” pattern. It also features thick, bushy eyebrows and a low anterior hairline ⁹.

Acquired generalized hypertrichosis presents with reversible, slow growth of terminal hairs over the forehead, temples, flexors, and trunk. Patients will report a history of frequently implicated medications traumatic brain injury, or systemic disease (see above for a complete list).

In acquired hypertrichosis lanuginosa, fine lanugo hairs rapidly develop over the entire body. Mild forms localized to the face exist. Patients may report a history of malignancy ²⁴.

Several forms of congenital localized hypertrichosis exist. Hypertrichosis cubiti (hairy elbow syndrome) presents anywhere from birth to early childhood with hypertrichosis over the forearms and antecubital fossa. It is occasionally associated with short stature. Hairy palms and soles syndrome presents at birth. Hypertrichosis of the auricle presents during childhood or adolescence and favors males. Hypertrichosis of the eyebrows and nasal tip appear in adolescence. Anterior cervical hypertrichosis presents from birth to early childhood and is associated with a sensory and motor neuropathy, mental retardation, and hallux valgus. Posterior cervical hypertrichosis appears at birth and is associated with kyphoscoliosis ²⁵.

Becker melanosis (nevus) presents as a patch of hyperpigmentation with irregular borders on the upper trunk. Typically, the hyperpigmentation appears during childhood, with hypertrichosis developing later in the second decade of life. Patients with Becker melanosis may have associated asymmetry of the extremities and hyperplasia or hypoplasia underlying the affected areas; ipsilateral mammary hypoplasia is a common finding in women). There are reports of Becker melanosis arising in the context of genitourinary abnormalities (SNUB syndrome; supernumerary nipples, uropathies, and Becker melanosis). Becker melanosis can also be associated with hemimaxillofacial dysplasia, which presents as unilateral maxillary enlargement manifesting as facial asymmetry, gingival hyperplasia, and hypoplastic teeth ²⁶.

Nevoid hypertrichosis presents as a well-circumscribed area of overgrowth of terminal hairs. Primary nevoid hypertrichosis refers to an isolated finding with no extracutaneous associations. Secondary nevoid hypertrichosis is often seen in conjunction with lipodystrophy, hemihypertrophy, scoliosis, and vasculature abnormalities ²⁷.

Localized areas of hypertrichosis may be a sign of defects underlying the patch of hair, such as spinal dysraphism. The faun tail sign is a patch over the lumbosacral area signifying the presence of spina bifida occulta or diastematomyelia (split spinal cord). The hair collar sign is a ring of hypertrichosis that surrounds aplasia cutis or ectopic brain tissue ²⁸.

Porphyrias such as porphyria cutanea tarda and hepatoerythropoietic porphyria can present as hypertrichosis within sun-exposed areas. Patients will present with other symptoms of porphyria. The hypertrichosis associated with porphyria cutanea tarda often favors the lateral face. Patients will present with other stigmata of porphyria cutanea tarda including a blistering photosensitive eruption ²⁹.

Acquired localized hypertrichosis will present as hypertrichosis, hyperpigmentation, and epidermal hyperplasia at a site of friction. Patients will report a history of mechanical or iatrogenic insult to the area. It is important to note that there are several reports of localized hypertrichosis overlying areas of lupus panniculitis and morphea ⁵.

Hypertrichosis diagnosis

When a patient presents with generalized hypertrichosis, the first step in evaluation is to determine whether it is a congenital or acquired problem. This can generally be determined by patient history.

If the hypertrichosis appears to be of congenital origin, the next step is to determine whether fine, lightly colored lanugo hairs predominate (suggesting a diagnosis of congenital hypertrichosis lanuginosa), or if pigmented/terminal hairs predominate. If there is a predominance of pigmented/terminal hairs, the patient should be evaluated for a family history of hypertrichosis, maternal drug or alcohol intake, and orofacial, skeletal, ocular, or neurologic abnormalities that may suggest a rare genetic syndrome such as X-linked hypertrichosis, congenital generalized hypertrichosis with or without gingival dysplasia, hypertrichotic osteochondrodysplasia, Zimmerman-Laband syndrome, Coffin-Siris syndrome, Schinzel-Giedion midface retraction syndrome, Gorlin-Chaudry Moss syndrome, adducted thumbs syndrome, Barbar-Say syndrome, Amaurosis congenita, or CAHMR (cataracts, hypertrichosis, and mental retardation) syndromes ²¹.

If the hypertrichosis appears to be acquired, once again the next step is to determine whether terminal hairs or lanugo hairs predominate. If terminal hairs predominate in the setting of slow, progressive development of hypertrichosis, the patient should be screened for features suggestive of prepubertal hypertrichosis (Mediterranean or South Asian descent, familial hairiness, inverted tree pattern on the back). The patient should also be screened for symptoms of androgen excess such as the early development of axillary/pubic hair, virilization, acne, and increased androgen levels. These may suggest a diagnosis of hirsutism, as opposed to hypertrichosis. If terminal hairs predominate in the setting of rapid growth, a thorough evaluation of the patient’s drug intake, thyroid hormone levels, and nutritional status should take place. If a patient presents with the sudden appearance of acquired lanugo hairs, they should be screened for malignancy.

Hypertrichosis treatment

Treatment of hypertrichosis is basically hair removal. Several methods are available but need to be repeated regularly as hair continues to grow back. They may also cause scarring, dermatitis or hypersensitivity reactions.

• Repeated shaving
• Chemical epilation
• Electrolysis and thermolysis
• Waxing

More recently, laser hair removal has been proposed as a treatment option. The Nd:Yag laser, Alexandrite laser, and diode laser are the most efficacious hair removal lasers.

Depilatory creams typically contain calcium thioglycolate and barium sulfate and are effective though they may irritate the skin ³⁰.

Hypertrichosis prognosis

The prognosis of hypertrichosis varies, depending on the type of hypertrichosis. Hypertrichosis associated with genetic syndromes is generally lifelong. In the setting of drug-induced hypertrichosis, it is usually reversible with discontinuation of the medication.

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