Definition and Overview of Hair Loss in Children
Hair loss in children can be classified into acquired alopecia and congenital alopecia. Hair loss in children can be a manifestation of a systemic, metabolic, or immunologic disease or it can be a focal problem secondary to primary scalp disorders. Focal hair loss can be associated with nonscarring or scarring alopecia.
Epidemiology and Causes of Hair Loss in Children
Hair loss is a common disorder in children that is usually not life-threatening but can be associated with significant emotional or psychological stress. The causes of hair loss are different among the different age groups of children.
Pre-school children with hair loss can have congenital aplasia cutis, alopecia areata, or occipital alopecia. School-aged children with hair loss might have alopecia areata, trichotillomania, traction alopecia or tinea capitis. Adolescents, especially boys, might have androgenic alopecia. Additionally, the use of chemical hair products by adolescents can be associated with hair thinning or hair loss.
The most common causes of focal scarring alopecia in children are scalp trauma, aplasia cutis and as a complication to kerions. Tinea capitis can cause focal nonscarring alopecia.
Clinical Presentation of Hair Loss in Children
To understand the different presentations of hair loss in children, it is easier to address each etiology of hair loss alone.
Acquired Focal Alopecia
Tinea capitis is a fungus infection that causes patchy hair loss in children. The causative organism is the fungus known as Trichophyton tonsurans. Children usually present with circular patchy alopecia with scaling. Black dots are usually seen on a gray background. The black dots are broken hair. Boggy and pustular nodules, known as kerions, can also be seen in some children.
Alopecia areata is an autoimmune disease that can be also associated with other autoimmune disorders, such as Hashimoto thyroiditis. A physical examination usually reveals smooth, oval patches of hair loss that are not confined to the scalp. Alopecia areata can present with partial loss of scalp hair, complete loss of scalp hair, known as alopecia totalis, or complete loss of scalp and body hair, known as alopecia universalis.
Children with focal hair loss, broken hairs and otherwise a normal and healthy scalp might have trichotillomania. This condition is characterized by hair pulling by the child at times of psychological, emotional or physical stress.
Congenital Focal Alopecia
Aplasia cutis is a condition that is characterized by the focal absence of skin in certain parts of the body at birth. The child usually has a small and focal area of skin erosion that can be on the scalp. The eroded skin eventually heals, but hair fails to grow from the involved area.
Children born with an orange in color, waxy hairless well-demarcated plaque over the scalp might have a condition known as Nevus Sebaceous of Jadassohn. These nevi have the potential of malignant transformation.
Acquired Diffuse Alopecia
Children with malignancies, who have hypothyroidism, or who are receiving chemotherapy or radiotherapy, might develop diffuse alopecia. Retinoic acid and valproate are more commonly associated with hair loss due to telogen effluvium, while chemotherapeutic agents usually cause hair loss due to anagen effluvium.
Boys with a family history of androgenic alopecia might develop diffuse hair thinning, and eventually, male-pattern hair loss in their adolescence.
Febrile illness in neonates and young infants, in addition to anemia, can also cause hair loss.
Congenital Diffuse Alopecia
Some genetic disorders, such as congenital hypotrichosis, can be associated with diffuse nonscarring scalp hypotrichosis. Other genetic causes of diffuse alopecia include Netherton syndrome, Menkes Kinky Hair syndrome and trichothiodystrophy. These genetic causes of diffuse alopecia are usually associated with other anomalies and syndromic features.
Diagnostic Workup for Hair Loss in Children
The main tool in the identification of the most likely cause of hair loss in a child is adequate history taking and a complete physical examination.
Children who present with acquired focal alopecia should be evaluated for possible scalp fungal infections. Scraping off the affected scalp areas can provide samples for potassium hydroxide preparation or fungal culturing.
Children with suspected alopecia areata should undergo thyroid function testing because of the strong association between alopecia areata and Hashimoto’s thyroiditis.
Children with suspected telogen effluvium should undergo erythrocyte sedimentation rate, a complete blood count and a serum ferritin test due to the association between systemic diseases and iron deficiency anemia with this type of alopecia.
Hair mount examination by light and polarizing microscopy is helpful in the differentiation between the different types of hereditary causes of hair loss.
Treatment of Hair Loss in Children
The management of hair loss in children is dependent on the etiology of the hair loss. Children with confirmed tinea capitis should receive systemic antifungal treatment. Griseofulvin, terbinafine and itraconazole are the most commonly used agents for the management of tinea capitis in children.
The adequate diagnosis of alopecia areata usually means that the child does not need any specific treatment because hair regrowth within 1 year has been described in most cases. When the child or his or her caregivers want a specific treatment for the condition, the choice of the therapeutic agent should be based on the extent of involvement. Children with localized scalp involvement can receive topical and intralesional corticosteroids or minoxidil. Children with alopecia totalis or alopecia universalis should receive oral immunosuppressive therapy. The most commonly used systemic treatments for alopecia areata are methotrexate, sulfasalazine and systemic corticosteroids.
N-acetyl cysteine, behavior modification therapy, and sertraline have been used in the treatment of trichotillomania.
Unfortunately, most causes of congenital genetic diffuse alopecia cannot be treated nowadays. Children with syndromic causes of genetic diffuse alopecia usually have a severe form of hair loss that is associated with a poor prognosis.
The discontinuation of radiotherapy or chemotherapy is known to reverse anogen effluvium in most children who receive these therapies for the management of malignant disease. The identification of the cause of telogen effluvium, and addressing the etiology, usually results in hair regrowth within six to twelve months.
Boys with androgenic alopecia can receive topical minoxidil or finasteride. The response is usually good, but close follow-up is recommended.