Hypertrichose

Hypertrichosis is a condition characterized by excessive hair growth anywhere on the body beyond what is typical for a person’s age, sex, and race. It can be generalized, affecting most or all of the body, or localized to a specific area. Hypertrichosis is distinct from hirsutism, which is excessive hair growth in androgen-dependent patterns typically seen in women; hypertrichosis refers to non–androgen-driven hair growth.

Causes and classification: The condition can be congenital (present at birth) or acquired later in life. Congenital forms include generalized hypertrichosis and specific syndromes such as congenital hypertrichosis lanuginosa and Ambras syndrome, which involve abnormal hair development from birth. Acquired hypertrichosis arises due to factors such as medications (for example, certain drugs can promote hair growth), malnutrition or systemic illness, and, less commonly, malignancy. Localized variants may affect limited regions of the body and can occur in association with inflammatory or traumatic skin sites.

Pathophysiology: In congenital cases, genetic mutations influence hair follicle development and cycling, leading to persistent or abnormal hair growth. In acquired cases, external factors may stimulate the hair growth cycle or alter hair type, resulting in new or increased hair in non-typical patterns.

Diagnosis and management: Diagnosis relies on clinical examination, patient and family history, and exclusion of conditions that mimic hypertrichosis. When indicated, laboratory tests to assess androgen status and genetic testing for suspected syndromes may be used. Management is usually cosmetic and supportive, focusing on hair removal or reduction methods such as shaving, waxing, depilation, electrolysis, or laser therapy. Treatment of underlying causes may mitigate acquired forms. Prognosis varies with the underlying etiology and can range from persistent congenital hair growth to improvement after addressing a triggering condition.