Are You Confident of the Diagnosis?
Hypertrichosis is defined as an excessive amount of hair growth on any area of the body. The hair may be lanugo (fine hair that covers the fetus and is usually shed in utero or first few weeks of life), vellus, or terminal. There are many causes of hypertrichosis and the standard classification is based on distribution (generalized versus localized) and onset (congenital versus acquired). Emphasis herein will be on acquired hypertrichosis. The excellent review by Wendelin et al details the numerous congenital etiologies of hypertrichosis as well as localized hypertrichotic lesions.
Acquired generalized hypertrichosis is most often related to drug ingestion. It is characterized by gradual conversion of vellus to terminal hair, most prounounced on the forehead, temples, trunk, and extremities. The most common systemic drug culprits, divided by class, are as follows:
Anticonvulsants – Phenytoin
Immunosuppressives – Cyclosporine
Vasodilators – Diazoxide, Minoxidil
Antibiotics – Streptomycin
Diuretics – Acetazolamide
Photosensitizers – Psoralen
In addition, the topical glaucoma medication latanoprost, a prostaglandin analogue, has been shown to cause regional hypertrichosis of the eyelashes and eyelids. Capitalizing on this “adverse” effect, bimatoprost ophthalmic solution is now marketed for the sole indication of eyelash growth. Similarly, the development of a tremendously successful pattern hair loss drug, topical minoxidil, resulted after its apparent predilection for causing unwanted hair growth when given systemically for hypertension was appreciated.
Acquired hypertrichosis lanuginosa, also known as “malignant down,” is a paraneoplastic disease associated with internal malignancy, most commonly lung and colon, but also reported with many other neoplasms. It is characterized by a sudden transformation of all hair follicles to lanugo hair, and has a characteristic craniocaudal spread, often being most pronounced on the face. The abnormal hair growth may precede or follow the neoplasm, and is presumed to result from a not-yet-identified signaling molecule arising from the neoplasm that stimulates hair grown.
Generalized acquired hypertrichosis can also result from a variety of systemic conditions including central nervous system (CNS) disturbances (traumatic brain injury), acrodynia, infection (tuberculosis, AIDS), malnutrition (anorexia nervosa), and thyroid abnormalities (particularly hypothyroidism in children). Both the hereditary and acquired porphyrias may result in hypertrichosis with a predilection for the sun-exposed areas of the face.
The POEMS (poyneuropathy, organomegaly, endocrinopathy, M protein skin changes) syndrome may be associated with variety of cutaneous manifestions including hypertrichosis that is especially pronounced on the lower extremities. The newly decribed “H syndrome” is a genodermatosis characterized by indurated, hyperpigmented, and hypertrichotic skin mainly involving the middle to lower part of the body with other systemic manifestations arising by the third decade.
Who is at Risk for Developing this Disease?
Individuals with the malignancies, diseases, and drug exposures outlined above are at risk for the development of hypertrichosis.
What is the Cause of the Disease?
The mechanism for the development of hypertrichosis is largely unknown.
Systemic Implications and Complications
In and of itself hypertrichosis is of no medical consequence. Treatment of the underlying disease may be indicated. Discontinuation of a causative medication may be helpful.
When hypertrichosis is secondary to an underlying condition or drug exposure, eradication of the cause will often resolve the hypertrichosis. In the case of primary hypertrichosis or that which cannot be resolved by eradicating the cause (for example the transplant patient on cyclosporine where other immunosuppressives are not an option), a wide variety of treatment options are available, geared toward hair removal for cosmetic/psychosocial purposes.
Techniques for hair removal range from temporary (shaving, depilatory cream) to more permanent (electrolysis, laser hair removal), the choice of which depends upon a number of factors including extent and location of hair growth. Because the hair growth in hypertrichosis is not androgen-dependent as in the case of hirsutism, antiandrogen systemic therapies are not beneficial.
Optimal Therapeutic Approach for this Disease
Individual patient preferences play the largest role in selection of optimal depilation method.
Management varies widely depending on underlying cause of the hypertrichosis.
Unusual Clinical Scenarios to Consider in Patient Management
Many patients with hypertrichosis have been incorrectly diagnosed as having hirsutism. Hirsutism refers specifically to excessive hair growth in a female that occurs in androgen-sensitive areas of the body due to overproduction of androgen or end-organ sensitivity to androgens. Its causes and treatments differ significantly.
It should be kept in mind that there are several congenital syndromes in which generalized hypertrichosis is a secondary feature, and these should be considered in the appropriate clinical setting. These include the mucopolysaccharidoses, lipoatrophies, fetal teratogen exposures (hydantoin, alcohol), and several other rare syndromes such as Rubinstein-Taybi, Corrin-Siris, Brachmann-de Lange, and others.
What is the Evidence?
Wendelin, DS, Pope, DN, Mallory, SB. “Hypertrichosis”. J Am Acad Dermatol. vol. 48. 2003. pp. 161-79. (This is the most updated and comprehensive review of the subject.)
Olsen, EA, Olsen, EA. “Hypertrichosis”. Disoders of hair growth: diagnosis and treatment. 1993. pp. 315-36. (A thorough review of the topic .)
Glorio, R, Allevato, M, De Pablo, A. “Prevalence of cutaneous manifestations in 200 patients with eating disorders”. Int J Dermatol. vol. 39. 2000. pp. 348-53. (This study of inpatient with eating disorders shows the high prevalence of hypertrichosis in this population.)
Ibrahimi, OA, Avram, MM, Hanke, CW. “Laser hair removal”. Dermatol Ther. vol. 24. 2011. pp. 94-107. Excellent, updated and comprehensive review of laser/light devices for hair removal, including discussion of hair follicle anatomy and physiology and mechanism of action/ efficacy of devices in various patient populations.)
Molho-Pessach, V, Agha, Z, Glaser, B. “The H syndrome: a genodermatosis characterized by indurated, hyperpigmented, and hypertrichotic skin with systemic manifestations”. J Am Acad Dermatol. vol. 59. 2008. pp. 79-85. (This group from Israel describes 10 patients from six consanguineous families with hyperpigmented, hypertrichotic patches. They also have some hearing loss, hepatosplenomegaly and scrotal masses (with growth hormone deficiency and yhpergonadotropic hypogonadism with azoospermia). The group suggests that this is a multisystem autosomal recessive inherited disorder called the “H syndrome.”)
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