Hypertrichosis is defined as excessive hair growth anywhere on the body in both males and females. It is important to distinguish it from hirsutism, which is a term reserved for women who grow excessive amounts of terminal hair in androgen-dependent sites.
There are several ways to classify this condition. These are based on distribution (generalized vs. localized), age of onset (congenital vs. acquired), and hair type (vellus vs terminal).
Forms of generalized hypertrichosis include, but are not limited to, i. generalized congenital (which is further divided into i. lanuginosa congenita, i. universal and i. universalis congenita), i. prepubertal, i. acquired generalized and i. acquired fluff. Each differs in their etiology and clinical findings.
Hypertrichosis: There are several forms
Forms of localized hypertrichosis include, but are not limited to, i. localized congenital (congenital nevi, plexiform neurofibromas, melanosis/Becker’s nevus, nevoid hypertrichosis, spinal dysraphism, and hair collar sign), i. localized in hereditary and acquired systemic diseases and i. localized acquired.
Understanding lanugo, vellus, and terminal hairs is critical in evaluating a patient with presumed i. Lanugo hair is fine, unpigmented hair that covers the normal fetus. It is often several centimeters long. Within the first few weeks of life, downy 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” found on the face, arms, stomach and legs.
Terminal hair is coarse, thick hair found on the scalp, underarms, and pubic area. In men, terminal hairs are also found on the face. During puberty, vellus hair is replaced with terminal hair at androgen-dependent sites under the influence of testosterone.
Congenital generalized hypertrichosis is a feature of several rare hereditary syndromes in which genetic errors result in the dysfunction of proteins involved in hair follicle development. There is some evidence that exposure to drugs such as minoxidil in utero may predispose to i. congenital generalized.
L’hypertrichosis prepubertal is linked to elevated free and total testosterone levels in some patients. Drugs most often cause acquired generalized hypertrichosis:
Anti-inflammatory drugs such as benoxaprofen and corticosteroids
Vasodilators (diazoxide, minoxidil, prostaglandin E1)
Diuretics (acetazolamide)
Anticonvulsants (phenytoin)
Immunosuppressants (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, the i. acquired generalized can also be seen in traumatic brain injury, juvenile hypothyroidism, juvenile dermatomyositis, acromegaly, malnutrition, and advanced HIV infection.
There. acquired lanuginosa is considered a paraneoplastic phenomenon and in some cases precedes the diagnosis of cancer. The most common malignancies 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.
Different forms of i. localized congenital, including hypertrichosis cubits (hairy elbow syndrome), hairy palms and soles, i. of the auricle, i. of the nasal tip and i. anterior or posterior cervical are inherited in an autosomal dominant fashion. Tricomegaly of the eyelashes is the exception, as it is an autosomal recessive disorder. nevoid has a variable etiology.
Primary nevoid hypertrichosis occurs in the absence of extracutaneous associations. Secondary nevoid is associated with lipodystrophy, hemihypertrophy, scoliosis, and underlying vascular system abnormalities.
There are several inherited 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 synophria (single eyebrow), as well as i. on the forehead, lateral face, shoulders and back.
Rubinstein-Taybi syndrome is due to autosomal dominant mutations and leads to hypertrichosis of the lateral face, shoulders, and back. Porphyria Cutanea Tarda is a cause of i. in areas exposed to the sun.
Congenital melanocytic nevi are often associated with hypertrichosis that occurs during the infantile period of infancy. Plexiform neurofibromas, pathognomonic lesions for neurofibromatosis type I, also have associated hypertrichosis.
Acquired localized hypertrichosis is caused by repeated trauma, friction, irritation, or inflammation. For example, the i. localized it is often seen on the back of bag bearers, over a broken limb after casting, and over the rear neck in weight lifters. It can also be seen within vaccination sites and chickenpox scars.
Hypertrichosis at wart removal sites and laser hair removal have also been reported in the literature. Also the i. localized acquired can be iatrogenic; it has been described following therapy with PUVA, topical corticosteroids, tacrolimus, mercury- or iodine-containing creams, anthralin, and prostaglandin F-2 alpha analogues (latanoprost, bimatoprost).
In most cases of hypertrichosis, men and women are equally affected, with a few exceptions. There. prepubertal is common in healthy, Mediterranean or South Asian infants and children. There. of the auricle and the i. of the nasal tip, types of i. hereditary, mainly affecting males.
The pathophysiology of i. varies according to the etiology. Genetic abnormalities underlie several types of i. and the pathogenesis of increased hair growth is unknown. On histopathological examination, the i. appears as an increase in the number of terminal hairs or vellus, depending on the etiology of hypertrichosisw.
When a patient has generalized hypertrichosis, the first step in evaluation is to determine whether the problem is congenital or acquired. This can generally be determined by the patient’s history.
If hypertrichosis appears to be congenital in origin, the next step is to determine whether fine, lightly colored lanuginous hairs predominate (suggesting a diagnosis of I. lanuginosa congenita) or 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 use, and orofacial, skeletal, ocular, or neurologic abnormalities that may suggest a rare genetic syndrome such as X-hypertrichosis connected, i. congenital generalized with or without gingival dysplasia, hypertrichotic osteochondrodysplasia, Zimmerman-Laband syndrome, Coffin-Siris syndrome, Schinzel-Giedion midfacial retraction syndrome, Gorlin-Chaudry Moss syndrome, adducted thumbs syndrome, Barbar-Say syndrome, congenital amaurosis.
If the i. appears to be acquired, again the next step is to determine whether terminal hairs or lanugo hairs predominate. If terminal hairs predominate in the context of slow progressive development of i., the patient should be screened for features indicative of i. prepubertal (Mediterranean or South Asian ancestry, familial hairiness, inverted tree structure on the back).
The patient should also be screened for symptoms of androgen excess such as 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 a setting of rapid growth, a thorough evaluation of the patient’s medication intake, thyroid hormone levels, and nutritional status should be made.
Laser hair removal, depilatory creams and electrolysis are used to remove unwanted hair. Nd:Yag laser, Alexandrite laser and diode laser are the most effective lasers for hair removal. Hair removal creams typically contain calcium thioglycolate and barium sulfate and are effective, although they can irritate the skin.
When considering a diagnosis of hypertrichosis, the main differential diagnosis is hirsutism. Hypertrichosis can be seen in both females and males, while hirsutism is a term used to describe male-pattern terminal hair growth in females, within androgen-dependent sites. Hirsutism is caused by an increase in androgens and is associated with other signs of androgen excess.
Different laser and light treatments are suitable for hair removal, depending on the patient’s Fitzpatrick skin type. Suitable technologies include the 755 nm alexandrite laser, 1064 nm Nd:Yag laser, diode laser, intense pulsed light (IPL), and electrolysis.
Hypertrichosis can cause severe emotional distress for patients, especially those who don’t have access to permanent laser hair removal or electrolysis. Self-confidence and quality of life may be extremely low for these patients due to social control and bullying in patients of all ages.
In cases of severe hypertrichosis, it is imperative to organize mental health care for patients in addition to medical care to address the underlying cause of the hypertrichosis, if any. The outcome of patients with hypertrichosis depends on the cause. For those with hereditary ailments, there is no cure and poor cosmetics is a lifelong problem. For those with acquired hypertrichosis, outcomes are good once the primary condition is treated or the offending drug is stopped.
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