What defines hypertrichosis?

Hypertrichosis is defined as excessive hair growth in areas of the body where hair is typically fine or minimal, or even in locations where hair is not normally present. This condition can affect both men and women, and it differs from hirsutism, which specifically refers to excessive hair growth in women following male-pattern hair distribution due to hormonal influences.

Excessive hair growth can manifest in different patterns and is not limited to specific body regions; it can occur all over the body, affecting both areas that usually have hair, such as the arms and legs, as well as areas that rarely grow hair, such as the face. This sets hypertrichosis apart from conditions like hair thinning, patchy hair loss, or balding patterns, which generally indicate a reduction in hair quantity or localized hair loss. Understanding this definition is crucial in recognizing the various hair growth conditions, their characteristics, and the terminology used in dermatologic contexts.