A clinical evaluation of hypertrichosis is important for an accurate diagnosis

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Clinical Evaluation of Hypertrichosis

Hypertrichosis is an excessive hair growth disorder characterized by only abnormal hair length and hair density compared to the patient’s respective racial, sex or age group. Importantly it is, with rare exceptions, not androgen related growth.

Evaluation of hypertrichosis must precede treatment since, besides being a cosmetic problem; it could be a sign of general medical problems.

The first step in hypertrichosis evaluation is clearly distinguishing it from normal hair growth, which includes:
- Identifying the hair/hairs involved
- Hair growth pattern
- Examination of the growth sites
- Examination of the degree of hypertrichosis

The patient’s background such as ethnicity, family history and the person’s age and sex must be investigated to remove any subjective assessment of excess growth. People from some ethnic backgrounds, such as, the Mediterranean people, generally have more hair on their body. They are not diagnosed as hypertrichosis affected, whereas, similar hair growth in people from other ethnic backgrounds could be a cause for concern. Often excess hair growth is a family trait. Women in advanced age sometimes have more facial hair, which many find disturbing, though for that age it could be normal.

Hypertrichosis then must be distinguished from hirsutism. Innumerable times hypertrichosis has been wrongly identified as hirsutism, which is a male pattern hair growth in infants and women and is caused by excess androgen.

Hypertrichosis involves three types of hair. These are lanugo, vellus and terminal hairs. Lanugo hairs are un-pigmented, long and silky and grow in vitro from the third month onwards covering the entire foetus. By the seventh or eighth month they shed entirely and are replaced by vellus hairs on the body and terminal hairs on the scalp. Vellus are short, fine non-pigmented hairs. Terminal hairs are longer than vellus hairs but coarser and respond to hormonal influences.

To make evaluation simple, hypertrichosis has been classified as generalized hypertrichosis and localized hypertrichosis. Generalized hypertrichosis involves all three types of hair and localized hypertrichosis involves mostly the terminal hairs. It should be noted well that hirsutism involves only terminal hairs.

Generalized hypertrichosis refers to even distribution of excess hair throughout the body as well as to excess growth on multiple sites. Localized hypertrichosis refers to growth on a single or very few sites. These two types are further sub-divided into congenital and acquired sub-types.

Generalised Congenital Hypertrichosis / GCH

Here typically the entire body except sites where hair normally does not grow is covered with lanugo hairs. Only the scalp hair, eyebrows and eyelashes are darker. Growth is more on the face, ears and shoulders. In not a single case was there subsequent decrease of hair. A variant of GCH is congenital hypertrichosis lanuginose where the body except for hands and feet is covered with excess hair at birth or early infancy. Except for dental eruptions the patients are normal.

In another variant called prepubertal hypertrichosis, the excess hair at birth spreads to the forehead and eyebrows. Upper back and proximal limbs show excess hair. It is different than the other two variants as the hairs are terminal.

The Bachmann de Lange variant in infants is less generalized but the infants can be easily recognized from their characteristic and stable appearance. This includes distinctive faces, low to secondary hairline, penciled but not bushy eyebrows, long eyelashes and thin lips. They also have constant abnormalities such as mental and growth retardation.

Generalized Acquired Hypertrichosis / GAH

GAH, induced by drugs such as phenytoin, cyclosporine and minoxidil in both its oral and topical form is more common. Hair growth usually becomes normal after discontinuation of the drugs.

Phenytoin affects the limbs, trunks and the face.

Cyclosporine affects children more. The estimated incidence of hypertrichosis in patients given this drug after organ transplant ranges from 24% to 94%.

Oral minoxidil used for hypertension causes hypertrichosis in almost all patients, male and female alike.

The non-drug induced causes of GAH include cerebral problems, tuberculosis in children, thyroid abnormalities and acquired porphirias.

Hypertrichosis is seen in around 80% cases of POEM. Hair growth is generalized but more in the lower extremities.

A kind of lanuginose is evaluated as acquired hypertrichosis. Lanuginose also known as ‘malignant down’ and is usually associated with lung and colon disorders. But there are cases where no underlying cause was found.

Localized congenital hypertrichosis

Congenital nevocellular nevi are associated with increased hair in the injured area but the presence of hair has no prognostic implication.

Smooth muscle harmatoma is a slightly hyperpigmented pebbly patch often on the trunk and involves vellus hairs indicating increased hair size rather than density.

Hypertrichosis cubiti or ‘hairy elbows’ is a localized growth on the elbows at birth, which increases in infancy and becomes partially or completely normal during adolescence.

Localized hair growth on the spine may be evaluated as spinal hypertrichosis and is sometimes a sign of occult neural disorders or spinal defects. Hair on the lower back known as ‘faun tail’ also indicates spinal defects.

Localized acquired hypertrichosis

Such hypertrichosis results when vellus hair transforms into terminal and is usually caused by injury, inflammation and irritation.

Becker’s nevus is a localized hair growth on the shoulders, anterior chest and scapular regions caused usually by sunburn. It affects men and women equally but women report the disorder more since it is a rare instance of androgen driven hypertrichosis.

Aids may cause localized growth on the eyelashes, eyebrows and ears.

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