Congenital Hair Follicle Deficiency (Hypotrichosis)

Notably, most pediatric hair loss issues are “acquired”, such as tinea capitis (fungal infection of the scalp), alopecia areata, and trichotillomania (hair loss from compulsive hair pulling). These are forms of “alopecia” where children who are born with normal hair, experience hair loss.

Hypotrichosis is the medical term for congenital hair follicle deficiency; unlike alopecia disorders that cause loss of existing hair, Congenital Hypotrichosis is a group of disorders where individuals are born with some form of hair follicle deficiency.

Congenital Hypotrichosis is usually caused by a genetic anomaly, or from an abnormality that occurs during embryonic development. There are numerous disorders that cause hypotrichosis, the following are a few of the more common or interesting examples.

Aplasia Cutis Congenita
Aplasia Cutis Congenita (ACC), is the medical description for non-growth or absence (i.e. aplasia), of skin (i.e. cutis), at birth (i.e. congenita).

ACC is therefore an embryonic developmental defect where the skin fails to develop normally; the newborn is born with an area where the skin is absent, similar to an open wound. When this birth defect involves the scalp it is frequently located in the back of the head, in the whole area. As the defect or defects heal there is a characteristic dense scar formation, devoid of hair follicles.

Our Experience with ACC
We have noted that the extraordinarily dense scar tissue, from ACC, is different than other types of scalp scarring and as such does not usually respond well to typical treatments with follicular unit grafts. Subsequently, graft growth rates are typically very poor. In our experience, it is best to first excise the areas of dense scar tissue. The residual hair follicle deficiency and scarring can then be treated with “chubby” follicular unit grafts, if needed. The above before and after photographs show the results following surgical treatment (requiring three procedures) in a patient with multiple areas of hyper-dense bald scar tissue from ACC.

Triangular Alopecia
Triangular alopecia can be present at birth but is frequently apparent after the age of 2, affecting one side of the temporal region (i.e. side of the scalp).

There is frequently a characteristic triangular shaped area where vellus like hair is present. Unlike ACC, there is no skin defect at birth, only hypotrichosis, which can be treated with routine follicular unit grafting techniques.

Setleis Syndrome
A very rare genetic syndrome that is also associated with temporal alopecia is Setleis syndrome. Unlike Triangular Alopecia, Setleis syndrome can have absence of the temporal skin at birth, like ACC, and develop scar tissue or cause a less severe birth defect with atrophic skin changes, more like triangular alopecia.

Congenital Atrichia
Congenital atrichia is a peculiar condition caused by a gene defect. It is frequently described as a total absence of hair at birth, that is sometimes associated with papular lesions on the face, body and limbs.

Curiously newborns with this genetic defect may be born with normal scalp hair follicles, that are lost in early childhood; these patients may therefore be misdiagnosed as having alopecia universalis. Researchers believe that a defect in the dermal papilla prevents the hair follicles from regenerating after entering the telogen phase, of the hair growth cycle. As a result, as each hair follicle enters telogen, for the first time, it can never regenerate and is therefore permanently lost. There is no known treatment.

Congenital Sebaceous Nevus
Congenital sebaceous nevus, also called, nevus sebaceous of Jadassohn is a congenital sebaceous gland hamartoma. These sebaceous nevi can involve the scalp and face. They are present at birth, devoid of normal hair follicles and can change at puberty, becoming thicker and greasy, when the sebaceous glands begin to proliferate.

These unpleasant nevi have a low but real potential for malignant transformation; they usually degenerate into basal cell carcinoma of squamous cell carcinoma. Lifetime risk of malignant degeneration is around 10%. When possible these lesions should be excised; residual scarring can be repaired using hair restoration surgery techniques.

Disclaimer
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