Introduction
Hypertrichosis refers to excessive hair growth, which can be present anywhere on the body. Hypertrichosis is a condition that can affect men or women, and can be present at birth or acquired later in life. Excessive hair growth can range from small patches of growth to full body coverage. This article gives insight into hypertrichosis in detail.
What Does Hypertrichosis Mean?
Hypertrichosis is a condition in which excessive hair growth is present in the body of males or females. Excessive hair growth can be due to congenital or acquired causes. Hypertrichosis can be generalized or localized. Congenital hypertrichosis is a rare condition. Acquired forms of hypertrichosis are more common. Hirsutism is commonly seen in women between 18 and 45 years of age.
How Is Hypertrichosis Different From Hirsutism?
Hirsutism and hypertrichosis are different conditions. Hypertrichosis refers to excessive hair growth, which can be present anywhere in the body of males and females. Hirsutism is a condition that affects females and not males. It refers to excessive hair growth in androgen-dependent areas of the female body.
What Are the Causes of Hypertrichosis?
Hypertrichosis can be caused by genetic mutations or acquired causes such as cancer, anorexia, hyperthyroidism, or certain drugs. Medications such as Phenytoin (anticonvulsants), Cyclosporine (immunosuppressants), Minoxidil and Diazoxide (vasodilators), Streptomycin (antibiotics), Acetazolamide (diuretics), and Psoralen (photosensitizers) can cause generalized or localized hypertrichosis. The acquired hypertrichosis caused by these medications is reversible if the medications are stopped.
What Are the Types of Hypertrichosis?
Hypertrichosis can be classified into generalized or localized hypertrichosis or congenital or acquired hypertrichosis. It includes the following:
Congenital Hypertrichosis
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Hypertrichosis Lanuginosa:
Lanugo hair is a very thin, unpigmented, downy hair that is present on the body of the fetus or newborn. It normally sheds before birth but is sometimes present at birth. It usually sheds before birth and is replaced by vellus hair. Hypertrichosis lanuginosa is a condition in which the newborn is completely covered with lanugo hair. However, it does not affect the palms of the hands, soles of the feet, and mucous membranes. The lanugo hair may thin and leave limited areas of hypertrichosis as the person ages.
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Generalized hypertrichosis:
In congenital generalized hypertrichosis, males exhibit excessive facial and upper body hair, and females exhibit less severe asymmetrical hair distribution. It does not affect the palms, soles, and mucous membranes.
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Terminal Hypertrichosis:
Terminal hair refers to thick and long hair compared to vellus hair. This condition is characterized by the presence of pigmented terminal hair that covers the entire body. It is also accompanied by gingival overgrowth. This form of hypertrichosis is referred to as werewolf syndrome because of the presence of thick and dark hair.
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Circumscribed Hypertrichosis:
Circumscribed hypertrichosis is characterized by the presence of thick vellus hair on the upper half of the body, specifically on the extremities. It is usually restricted to the extensor surfaces of the upper extremities. In hairy elbow syndrome, excessive hair growth is present on and around the elbows. Circumscribed hypertrichosis is present at birth. This becomes prominent during aging and regresses during puberty.
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Localized Hypertrichosis:
It represents a localized increase in the density and length of the hair.
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Nevoid Hypertrichosis:
It may be present during birth or acquired later in life. It represents an isolated area of excessive terminal hair and is not related to any other medical conditions.
Acquired Hypertrichosis
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Hypertrichosis Lanuginosa:
Acquired lanuginosa refers to the rapid growth of lanugo hair, specifically on the face. Hair growth is also seen on the trunk and armpits. However, palms and soles remain unaffected. The hair appears very fine and unpigmented and is referred to as malignant down.
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Generalized Hypertrichosis:
Acquired generalized hypertrichosis affects the cheeks, upper lip, and chin. It also affects the forearms and legs. It is also associated with multiple hairs which occupy the same follicle. It also causes trichiasis, an abnormal growth pattern of the eyelashes. Oral Minoxidil tablets prescribed for hypertension can cause this condition. Topical Minoxidil for alopecia causes hair growth in areas of application, but it disappears after discontinuing Minoxidil.
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Patterned Hypertrichosis:
Patterned hypertrichosis is similar to acquired generalized hypertrichosis. It causes excessive hair growth in a pattern and is a sign of internal malignancy.
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Localized Hypertrichosis:
It represents increased hair density and length secondary to irritation or trauma. It is restricted to certain areas of the body.
What Are the Signs and Symptoms of Hypertrichosis?
The signs and symptoms of hypertrichosis are the presence of excessive hair. Hair is longer than usual and can be of lanugo, vellus, or terminal hair type. Patterned hypertrichosis presents with pattern formation. Generalized forms affect the entire body, and circumscribed and localized forms affect certain areas of the body.
How Does Hypertrichosis Occur?
Various mechanisms can cause hypertrichosis. One of the reasons is the areas of the skin that transform vellus hair into the terminal type. This type of transformation is seen during adolescence, in which vellus hair follicles in the underarms grow into terminal hair follicles. In hypertrichosis, such a transformation occurs in areas that do not produce terminal hair normally. Another mechanism involves the changes in the hair cycle. The hair cycle involves an anagen phase, catagen phase, and telogen phase. If the anagen phase exceeds normal, that region of the body shows excessive hair growth.
How Is Hypertrichosis Diagnosed?
The diagnosis depends on the history and the clinical appearance of the individual. Hypertrichosis is diagnosed if excessive hair growth is seen in areas that are not androgen-sensitive.
How Is Hypertrichosis Treated?
The congenital forms of hypertrichosis cannot be cured. The treatment for acquired hypertrichosis is to address the underlying cause. However, all forms of hypertrichosis can be managed with temporary or permanent hair removal treatments. Trimming, shaving, depilation, plucking, electrology, waxing, sugaring, and threading can help in hair removal. Permanent removal methods use chemicals or lasers to remove hair.
Conclusion
Hypertrichosis is a rare disorder in which excessive hair growth is present throughout the body. It cannot be cured completely but can be managed with temporary or permanent hair removal methods. Various treatment methods are under research to control the overproduction of hair.
