Hypertrichosis: 9 Types, Causes, And Treatments Explained
Explore the causes, types, diagnosis, and management of hypertrichosis, the rare condition of excessive hair growth beyond normal patterns.
Hypertrichosis is defined as excessive hair growth over and above the normal amount for a person’s age, sex, and race. Unlike hirsutism, which follows a male-pattern distribution in women due to androgen influence, hypertrichosis can affect any body area and both sexes equally. It may be generalized across the body or localized to specific patches and can be congenital (present at birth) or acquired later in life.
What is the cause of hypertrichosis?
The aetiology of hypertrichosis varies by type. Congenital forms often stem from genetic mutations that reactivate fetal hair genes, such as lanugo production. For instance, congenital hypertrichosis lanuginosa involves persistent lanugo hair due to failure of normal shedding post-gestation. Acquired hypertrichosis may result from medications (e.g., phenytoin, ciclosporin, minoxidil), malnutrition, autoimmune diseases, infections, or underlying malignancies like cancer. Chronic irritation, trauma, or increased vascularity in localized areas can also trigger it. Porphyria cutanea tarda, a metabolic disorder, frequently causes facial hypertrichosis due to UV sensitivity.
Who gets hypertrichosis?
Hypertrichosis is rare, particularly congenital forms, with only about 50 cases of congenital hypertrichosis lanuginosa reported worldwide since the Middle Ages. It affects males and females equally, unlike hirsutism. Congenital generalized hypertrichosis has X-linked dominant inheritance, meaning affected females have a 50% chance of passing it to offspring, while affected males pass it only to daughters. Acquired forms occur in anyone exposed to triggers like drugs or disease, with no strong demographic bias.
What are the clinical features of hypertrichosis?
Excessive hair can be lanugo (fine, unpigmented), vellus (short, soft), or terminal (long, pigmented). In congenital cases, babies may present with lanugo covering the body, persisting lifelong. Generalized forms cover the entire body except androgen-sensitive areas (pubic, axillary). Localized types appear as patches, e.g., hairy elbows or sacral tufts. Associated features include gingival hyperplasia in terminalis forms, leading to dental anomalies or soft voices. Patterned hypertrichosis may signal malignancy.
How is hypertrichosis diagnosed?
Diagnosis is clinical, based on hair excess beyond normal for age, sex, ethnicity, and non-androgen sites. History distinguishes congenital from acquired (e.g., drug intake, malnutrition). Family history aids genetic forms. Biopsy shows normal hair follicles with increased density/length. Rule out underlying causes via blood tests, imaging, or malignancy screening if patterned or sudden onset.
What is the treatment for hypertrichosis?
Treatment targets cosmetics, as hypertrichosis is not harmful. Options include:
- Mechanical removal: Shaving, plucking, waxing, threading, or epilation devices for temporary relief.
- Chemical depilatories: Creams dissolving hair shafts, used cautiously to avoid irritation.
- Electrolysis: Permanent destruction of follicles via electric current; effective but time-consuming for large areas.
- Laser therapy: Nd:YAG or intense pulsed light (IPL) targets melanin; multiple sessions needed, less effective on light hair.
- Medications: Topical eflornithine for facial areas; address underlying causes (e.g., stop offending drugs).
Severity guides choice; severe congenital cases may require lifelong management.
Types of hypertrichosis
Hypertrichosis classifies by distribution, onset, and hair type.
Congenital hypertrichosis lanuginosa
Rare syndrome (~50 cases ever) where lanugo hair fails to shed at 8 months gestation, covering the body at birth and persisting as fine, silky hair lifelong.
Congenital hypertrichosis terminalis (Ambras/Generalized hypertrichosis terminalis)
Thick, pigmented terminal hair covers face/body from birth. Often with gingival hyperplasia. Genetic link to chromosome 17 or Xq24-27.1. Historical ‘werewolf’ cases.
Congenital circumscribed hypertrichosis (Hairy elbow syndrome)
Thick vellus hair on upper extremities, especially elbows; worsens with age, regresses at puberty.
Acquired generalized hypertrichosis lanuginosa
Develops postnatally, mimicking fetal lanugo; linked to drugs, cancer, or eating disorders.
Acquired hypertrichosis lanuginosa
Fine lanugo-like hair, often paraneoplastic (e.g., colorectal cancer).
Acquired hypertrichosis terminalis
Terminal hair growth from drugs (e.g., phenytoin, diazoxide), HIV, or anorexia.
Naevoid hypertrichosis
Patchy, any hair type; may associate with spina bifida or Becker naevus.
Patterned hypertrichosis
Symmetrical patterns signaling malignancy (e.g., jawline in AIDS).
Localized hypertrichosis
Due to irritation/trauma (e.g., cast sites, lichen simplex); reversible.
| Type | Onset | Distribution | Hair Type | Associations |
|---|---|---|---|---|
| Congenital lanuginosa | Birth | Generalized | Lanugo | Rare genetic |
| Congenital terminalis | Birth | Generalized | Terminal | Gingival hyperplasia |
| Acquired generalized | Later | Generalized | Lanugo/Vellus/Terminal | Drugs, malignancy |
| Localized | Later | Patches | Vellus/Terminal | Trauma, irritation |
Frequently Asked Questions
What is the difference between hypertrichosis and hirsutism?
Hypertrichosis is excess hair anywhere, not androgen-driven; hirsutism is male-pattern hair in women due to androgens.
Is hypertrichosis curable?
Congenital forms persist lifelong; acquired may resolve by treating cause. Hair removal manages symptoms.
Can medications cause hypertrichosis?
Yes, e.g., phenytoin, minoxidil, ciclosporin.
Is hypertrichosis linked to cancer?
Acquired lanuginosa or patterned forms can be paraneoplastic.
How effective is laser for hypertrichosis?
Good for dark hair; 5-10 sessions reduce 70-90%, but regrowth possible.
This article provides an in-depth overview, drawing from clinical dermatology insights. Consult a dermatologist for personalized advice.
References
- Hypertrichosis — Wikipedia. 2023-10-01. https://en.wikipedia.org/wiki/Hypertrichosis
- Hypertrichosis: Causes, symptoms, and types — Medical News Today. 2023-05-15. https://www.medicalnewstoday.com/articles/320048
- Hypertrichosis — DermNet NZ (Authoritative dermatology resource, peer-reviewed). 2024-01-20. https://dermnetnz.org/topics/hypertrichosis
- Hypertrichosis (Werewolf Syndrome): Causes, Treatments, and Types — Healthline. 2023-11-10. https://www.healthline.com/health/hypertrichosis
- Hirsutism and Hypertrichosis — Merck Manual Professional Edition (Official medical reference). 2024-09-01. https://www.merckmanuals.com/professional/dermatologic-disorders/hair-disorders/hirsutism-and-hypertrichosis
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