Prepubertal hypertrichosis is a medical condition characterized by the excessive growth of hair in children before they reach puberty. This involves a noticeable increase in hair density, length, or coarseness in areas where hair growth is usually minimal or fine in prepubescent individuals.
Understanding Prepubertal Hypertrichosis
Hair can be classified into different types: vellus hair, which is fine, short, and often lightly pigmented, and terminal hair, which is coarser, longer, and usually pigmented, like the hair on the scalp or eyebrows. In prepubertal hypertrichosis, there can be an increase in either vellus or terminal hair, or a conversion of vellus to terminal hair in unusual locations.
The excessive hair growth can occur across the entire body, known as generalized hypertrichosis, or it can be limited to specific areas, referred to as localized hypertrichosis. Common areas for generalized growth include the face, particularly the forehead, temples, and around the ears, as well as the back and limbs. In some cases, the hair on the back may grow in an “inverted fir tree” pattern, and children might also have bushy eyebrows and a low hairline. Localized forms can manifest in specific regions, such as lumbosacral hypertrichosis, which is excessive hair growth on the lower back.
Underlying Causes and Associated Conditions
The causes of prepubertal hypertrichosis are varied, encompassing both inherited and acquired factors. Some cases are congenital and may be linked to specific genetic syndromes. For instance, conditions like Cornelia de Lange syndrome, Coffin-Siris syndrome, and Cantú syndrome can feature hypertrichosis as part of their presentation. Genetic errors affecting hair follicle development can also be responsible for congenital generalized hypertrichosis.
Acquired forms can be triggered by external factors or underlying health issues. Certain medications are known to induce hypertrichosis as a side effect. These include phenytoin, often used for seizures; cyclosporine, an immunosuppressant; and minoxidil, a vasodilator sometimes used for hair growth. Other drugs like corticosteroids, diazoxide, and penicillamine can also lead to increased hair growth.
Underlying medical conditions can also contribute to prepubertal hypertrichosis. Hypothyroidism, an underactive thyroid, can result in hypertrichosis due to its impact on hair growth regulation. Anorexia nervosa, a severe eating disorder, and dermatomyositis, an inflammatory muscle disease, have also been associated with this condition. Rarely, tumors can be a cause, and some cases are linked to elevated levels of free and total testosterone, although this is distinct from hirsutism, which is primarily driven by androgen excess.
Diagnosis and Assessment
Diagnosis of prepubertal hypertrichosis aims to identify its underlying cause. This begins with a detailed medical history, where the healthcare provider will inquire about the age of onset of the hair growth, any family history of similar conditions, and a comprehensive review of all medications the child is currently taking or has taken. Information regarding the child’s general health, including any other symptoms or developmental milestones, is also gathered.
A physical examination is performed to assess the extent, distribution, and characteristics of the excessive hair growth. This includes noting the type of hair (vellus or terminal) and whether the growth is generalized or localized to specific body areas. The healthcare provider will also look for any other physical signs that might suggest an associated syndrome or underlying medical condition.
Various diagnostic tests may be ordered. Blood tests are commonly used to check hormone levels, such as thyroid function and androgen levels, to rule out hormonal imbalances. In cases where a genetic syndrome is suspected, genetic testing might be recommended. If there is concern about an underlying tumor, particularly in cases of localized hypertrichosis, imaging studies like an MRI may be performed to visualize internal structures. A skin biopsy can also be used to examine hair follicles and rule out other skin conditions.
Management and Outlook
Managing prepubertal hypertrichosis primarily focuses on addressing the identified underlying cause. If the excessive hair growth is a side effect of a medication, discontinuing or adjusting the dosage of that medication, in consultation with the prescribing doctor, often leads to a reversal of the condition. Similarly, if an underlying medical condition like hypothyroidism is diagnosed, treating that condition can help reduce hair growth.
For cases where the underlying cause cannot be treated directly, or for cosmetic concerns, various hair removal methods can be considered, keeping in mind the child’s age and skin sensitivity. Temporary methods include shaving, trimming, or using depilatory creams. Shaving does not alter hair thickness or growth rate, but can cause skin irritation. Permanent hair reduction options, such as laser hair removal or electrolysis, may be pursued under medical supervision, although these can be painful and may not always be covered by insurance.
The long-term outlook for prepubertal hypertrichosis varies depending on its cause. If the condition is drug-induced, hair growth typically reverses once the medication is stopped. However, if hypertrichosis is part of a genetic syndrome, it is generally a lifelong condition, requiring ongoing management of the hair and any associated symptoms. Psychological support can also be beneficial for children and their families, as excessive hair growth can impact self-esteem and social interactions.