Hypertrichosis is defined as excessive hair growth anywhere on the body in either males or females. It is important to distinguish hypertrichosis from hirsutism, which is a term reserved for females who grow an excessive amount of terminal hairs in androgen-dependent sites.
There are several ways of classifying hypertrichosis. These are based on the distribution (generalized vs. localized), the age of onset (congenital versus acquired), and the type of hair (vellus versus terminal).
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 etiology and clinical findings.
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.
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.
Congenital generalized hypertrichosis is a feature of several rare inherited syndromes in which genetic errors result in the dysfunction of proteins involved in the development of the hair follicle. There is some evidence to support that exposure to medications such as minoxidil in utero may predispose to congenital generalized hypertrichosis.
Drugs most often cause acquired generalized hypertrichosis.
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.
Acquired hypertrichosis lanuginosa is considered to be a paraneoplastic phenomenon, and in certain instances precedes the diagnosis of cancer. 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.
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. Trichomegaly of the eyelashes is the exception, as it is an autosomal-recessive disorder.
Congenital melanocytic nevi are often associated with hypertrichosis that becomes apparent during the infantile period of childhood. Plexiform neurofibromas, lesions pathognomonic for neurofibromatosis type I, also have associated hypertrichosis.
Nevoid hypertrichosis has a variable etiology.
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. Rubinstein-Taybi syndrome is due to autosomal-dominant mutations and leads to hypertrichosis over the lateral face, shoulders, and back. Porphyria cutanea tarda is a cause of hypertrichosis in sun-exposed areas. Lipodystrophy syndromes, such as Berardinelli-Seip syndrome caused by AGPAT2, BSCL2, CAV1, CAVIN1/PTRF gene mutations, can present with hypertrichosis as well.
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. 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 analogs (latanoprost, bimatoprost).
In the majority of hypertrichosis cases, men and women are equally affected, with a few exceptions. Prepubertal hypertrichosis is common in healthy, Mediterranean, or South Asian infants and children. Hypertrichosis of the auricle and hypertrichosis of the nasal tip, types of hereditary hypertrichosis, primarily affect males.
The pathophysiology of hypertrichosis varies depending on the etiology. Genetic abnormalities underlie several types of hypertrichosis, and the pathogenesis of increased hair growth is unknown.
On histopathology, hypertrichosis appears as an increased number of terminal or vellus hairs, depending on the etiology of the hypertrichosis.
History and physical exam findings for hypertrichosis 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.
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 are 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.
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 as "exaggerated normal hairiness."
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.
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.
Acquired generalized hypertrichosis presents with the 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 etiology section 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.
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 sensory and motor neuropathy, mental retardation, and hallux valgus. Posterior cervical hypertrichosis appears at birth and is associated with kyphoscoliosis.
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.
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.
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.
Porphyrias such as porphyria cutanea tarda (PCT) and hepatoerythropoietic porphyria (HEP) can present as hypertrichosis within sun-exposed areas. Patients will present with other symptoms of porphyria. The hypertrichosis associated with PCT often favors the lateral face. Patients will present with other stigmata of PCT including a blistering photosensitive eruption.
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.
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.
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 the 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.
Laser hair removal, depilatory creams, and electrolysis are used to remove unwanted hair. 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.
When considering a diagnosis of hypertrichosis, the major 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 women, within androgen-dependent sites. Hirsutism is caused by increased androgens and is associated with other signs of androgen excess.
Several laser and light treatments are suitable for hair removal, depending on the Fitzpatrick skintype of the patient.
Suitable technologies include 755nm Alexandrite laser, 1064nm Nd:Yag laser, diode laser, intense pulsed light (IPL) and electrolysis. 
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.
If the hypertrichosis has a genetic component, patients should be intimated about the risk of their children inheriting the traits.
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.
|||Park AM,Khan S,Rawnsley J, Hair Biology: Growth and Pigmentation. Facial plastic surgery clinics of North America. 2018 Nov [PubMed PMID: 30213423]|
|||Tng VE,de Zwaan S, Hypertrichosis cubiti, a case report and literature review. Clinical case reports. 2016 Feb [PubMed PMID: 26862409]|
|||Mimoto MS,Oyler JL,Davis AM, Evaluation and Treatment of Hirsutism in Premenopausal Women. JAMA. 2018 Apr 17 [PubMed PMID: 29522641]|
|||Frank JA,Rojek N,Foreman RS, A case of hypertrichosis lanuginosa acquisita as a sign of malignancy. European journal of dermatology : EJD. 2017 Feb 1 [PubMed PMID: 27748263]|
|||Nguyen KD,Osehobo E,Alleyne CH Jr, Hypertrichosis lanuginosa acquisita associated with intracranial melanoma: case illustration. Journal of neurosurgery. 2018 Jul [PubMed PMID: 28707995]|
|||Lee IJ,Im SB,Kim DK, Hypertrichosis universalis congenita: a separate entity, or the same disease as gingival fibromatosis? Pediatric dermatology. 1993 Sep [PubMed PMID: 8415305]|
|||Hernandez MI,Castro A,Bacallao K,Avila A,Espinoza A,Trejo L,Iñiguez G,Codner E,Cassorla F, Hormonal profile and androgen receptor study in prepubertal girls with hypertrichosis. International journal of pediatric endocrinology. 2014 [PubMed PMID: 24745883]|
|||Salido R,Gómez-García FJ,Garnacho-Saucedo G,Galán-Gutiérrez M, Acquired generalized hypertrichosis due to diazoxide. Actas dermo-sifiliograficas. 2013 Mar [PubMed PMID: 22989667]|
|||Kim WI,Kim TW,Park SM,Lee HJ,Jin H,You HS,Shim WH,Kim GW,Kim HS,Kim BS,Kim MB,Ko HC, Plexiform Schwannoma with Localized Hypertrichosis. Annals of dermatology. 2018 Aug [PubMed PMID: 30065605]|
|||Poonia K,Gogia P,Bhalla M, Localized Hypertrichosis at Vaccination Site. International journal of trichology. 2018 May-Jun [PubMed PMID: 30034196]|
|||Manchanda K,Mohanty S, Localized Hypertrichosis Following Vaccination in an Infant. International journal of trichology. 2016 Apr-Jun [PubMed PMID: 27601863]|
|||Pérez-López I,Martinez-López A,Blasco-Morente G,Ruiz-Villaverde R, Faun Tail Nevus: A Cutaneous Sign of Spinal Dysraphism. Actas dermo-sifiliograficas. 2017 Jan - Feb [PubMed PMID: 27208911]|
|||Chien MM,Chen KL,Chiu HC, The [PubMed PMID: 26601906]|
|||Kaler SG,Patrinos ME,Lambert GH,Myers TF,Karlman R,Anderson CL, Hypertrichosis and congenital anomalies associated with maternal use of minoxidil. Pediatrics. 1987 Mar [PubMed PMID: 3547299]|
|||Gryngarten M,Bedecarràs P,Ayuso S,Bergadà C,Campo S,Escobar ME, Clinical assessment and serum hormonal profile in prepubertal hypertrichosis. Hormone research. 2000 [PubMed PMID: 11182631]|
|||Elosua-González M,Campos-Domínguez M,Bancalari D,Noguera-Morel L,Hernández-Martín A,Huerta-Aragonés J,Torrelo A, Omeprazole-induced hypertrichosis in two children. Pediatric dermatology. 2018 Jul [PubMed PMID: 29582462]|
|||Imbernón-Moya A,Podlipnik S,Burgos F,Vargas-Laguna E,Aguilar-Martínez A,Fernández-Cogolludo E,Gallego-Valdes MA, Acquired Localized Hypertrichosis Induced by Rivastigmine. Case reports in dermatological medicine. 2016 [PubMed PMID: 27073702]|
|||Tan AR, Cutaneous manifestations of breast cancer. Seminars in oncology. 2016 Jun [PubMed PMID: 27178684]|
|||Tančić-Gajić M,Vujović S,Dujmović I,Basta I,Ivović M,Marina LV,Djordjević PB,Micić D, Acquired Hypertrichosis Lanuginosa: Typical Presentation and Unusual Association. Archives of Iranian medicine. 2015 Jul [PubMed PMID: 26161711]|
|||Blasco-Morente G,Sánchez-Carpintero I, Isolated Anterior Cervical Hypertrichosis. Actas dermo-sifiliograficas. 2017 Sep [PubMed PMID: 27979307]|
|||Fernández-Crehuet P,Ruiz-Villaverde R, Essential Trichomegaly of the Eyelashes. International journal of trichology. 2016 Jul-Sep [PubMed PMID: 27625571]|
|||Mathieu M,Goldfarb A,Berquin P,Boudailliez B,Labeille B,Piussan C, Trichomegaly, pigmentary degeneration of the retina and growth disturbances. A probable autosomal recessive disorder. Genetic counseling (Geneva, Switzerland). 1991 [PubMed PMID: 1781955]|
|||Schaffer JV,Chang MW,Kovich OI,Kamino H,Orlow SJ, Pigmented plexiform neurofibroma: Distinction from a large congenital melanocytic nevus. Journal of the American Academy of Dermatology. 2007 May [PubMed PMID: 17280739]|
|||Hjira N,Boui M, [Nevoid hypertrichosis]. The Pan African medical journal. 2013 [PubMed PMID: 24147182]|
|||Gupta L,Gautam RK,Bharadwaj M, Nevoid hypertrichosis: case report with review of the literature. International journal of trichology. 2011 Jul [PubMed PMID: 22223975]|
|||Sharawat IK,Dawman L, Cornelia de Lange Syndrome: A Case Series from a Resource-Limited Country. Journal of pediatric neurosciences. 2018 Jul-Sep [PubMed PMID: 30271468]|
|||De Silva B, What syndrome is this? Rubenstein-Taybi syndrome. Pediatric dermatology. 2002 Mar-Apr [PubMed PMID: 11994187]|
|||González Fernández D,Vázquez-López F, [Woman with facial hypertrichosis]. Revista clinica espanola. 2014 Jun-Jul [PubMed PMID: 24796639]|
|||Gómez Moyano E,Martínez Pilar L,Fernandez Ballesteros MD,Godoy Diaz DJ, Porphyria cutanea tarda in a patient with hepatitis C. Medicina clinica. 2018 Feb 9 [PubMed PMID: 28416230]|
|||Haghighi A,Kavehmanesh Z,Haghighi A,Salehzadeh F,Santos-Simarro F,Van Maldergem L,Cimbalistiene L,Collins F,Chopra M,Al-Sinani S,Dastmalchian S,de Silva DC,Bakhti H,Garg A,Hilbert P, Congenital generalized lipodystrophy: identification of novel variants and expansion of clinical spectrum. Clinical genetics. 2016 Apr [PubMed PMID: 26072926]|
|||Özyurt S,Çetinkaya GS, Hypertrichosis of the malar areas and poliosis of the eyelashes caused by latanoprost. Actas dermo-sifiliograficas. 2015 Jan-Feb [PubMed PMID: 25065768]|
|||Barth JH,Wilkinson JD,Dawber RP, Prepubertal hypertrichosis: normal or abnormal? Archives of disease in childhood. 1988 Jun [PubMed PMID: 3389902]|
|||Veerraju P,Satyanarayana M, Hypertrichosis pinnae auris in Coastal Andhra population. Jinrui idengaku zasshi. The Japanese journal of human genetics. 1973 Jun [PubMed PMID: 4796359]|
|||Vinay K,Sawatkar GU,Dogra S, Hair manifestations of endocrine diseases: A brief review. Indian journal of dermatology, venereology and leprology. 2018 Sep-Oct [PubMed PMID: 30027913]|
|||Shah IH,Zeerak S,Sajad P,Bashir S,Bhat YJ,Mubashir S, Congenital hypertrichosis lanuginosa. Indian journal of dermatology, venereology and leprology. 2018 [PubMed PMID: 28566560]|
|||Maza A,Gaudy-Marqueste C,Collet-Vilette AM,Joubert F,Richard MA,Grob JJ, [Congenital universal hypertrichosis]. Annales de dermatologie et de venereologie. 2009 Mar [PubMed PMID: 19328322]|
|||Chen W,Ring J,Happle R, Congenital generalized hypertrichosis terminalis: a proposed classification and a plea to avoid the ambiguous term [PubMed PMID: 25961852]|
|||Reddy Kundoor VK,Maloth KN,Kesidi S,Moni T, Ambras Syndrome with Gingival Hyperplasia: A Rare Entity. International journal of trichology. 2016 Apr-Jun [PubMed PMID: 27601862]|
|||León-Muiños E,Monteagudo B,Cabanillas M,Suárez-Amor O,Bermúdez E, [Hypertrichosis cubiti (hairy elbows syndrome)]. Anales de pediatria (Barcelona, Spain : 2003). 2009 Dec [PubMed PMID: 19726250]|
|||Kaliyadan F,Bhimji SS, Becker Melanosis null. 2018 Jan [PubMed PMID: 28613770]|
|||Mirfazaelian H,Sotoude H,Negahban S,Aledavood A,Daneshbod Y, A woman with hypertrichosis. British journal of hospital medicine (London, England : 2005). 2014 May [PubMed PMID: 25040278]|
|||Ma HJ,Yang Y,Ma HY,Jia CY,Li TH, Acquired localized hypertrichosis induced by internal fixation and plaster cast application. Annals of dermatology. 2013 Aug [PubMed PMID: 24003283]|
|||O'Byrne JJ,Laffan E,Murray DJ,Reardon W, Oculo-facio-cardio-dental syndrome with craniosynostosis, temporal hypertrichosis, and deafness. American journal of medical genetics. Part A. 2017 May [PubMed PMID: 28317252]|
|||Mégarbané A,Al-Ali R,Choucair N,Lek M,Wang E,Ladjimi M,Rose CM,Hobeika R,Macary Y,Temanni R,Jithesh PV,Chouchane A,Sastry KS,Thomas R,Tomei S,Liu W,Marincola FM,MacArthur D,Chouchane L, Temple-Baraitser Syndrome and Zimmermann-Laband Syndrome: one clinical entity? BMC medical genetics. 2016 Jun 10 [PubMed PMID: 27282200]|
|||Zhao P,Gao D,Huang Y,Lin J,Cai X,He X, [Clinical features and genetic analysis of a case with Coffin-Siris syndrome]. Zhonghua yi xue yi chuan xue za zhi = Zhonghua yixue yichuanxue zazhi = Chinese journal of medical genetics. 2018 Oct 10 [PubMed PMID: 30298501]|
|||Goldberg DJ, One-year follow-up results of hair removal using an 810 nm diode laser. Journal of cosmetic dermatology. 2018 Oct [PubMed PMID: 30251358]|
|||Nistico SP,Del Duca E,Farnetani F,Guida S,Pellacani G,Rajabi-Estarabadi A,Nouri K, Removal of unwanted hair: efficacy, tolerability, and safety of long-pulsed 755-nm alexandrite laser equipped with a sapphire handpiece. Lasers in medical science. 2018 Sep [PubMed PMID: 29654422]|
|||Shokeir H,Samy N,Mahmoud H,Elsaie ML, Evaluation of Topical Capislow Extract and Long Pulsed Nd-YAG Laser in the Treatment of Idiopathic Hirsutism. Journal of lasers in medical sciences. 2018 Spring [PubMed PMID: 30026898]|
|||Umar S, Selection criteria and techniques for improved cosmesis and predictable outcomes in laser hair removal treatment of acne keloidalis nuchae. JAAD case reports. 2019 Jun; [PubMed PMID: 31205997]|