Consider Trichoscopy for Suspected Hair Disorders

Doug Brunk

August 07, 2020

In the clinical experience of Bianca Maria Piraccini, MD, dermoscopic imaging of the scalp and hair can help physicians diagnose a variety of disorders that would normally require an invasive biopsy.

Dermoscopic imaging, also known as trichoscopy, "avoids invasive procedures and provides immediate results," Dr. Piraccini, of the University of Bologna's division of dermatology in the department of experimental, diagnostic, and specialty medicine, said during the virtual annual meeting of the Society for Pediatric Dermatology. "It is helpful for diagnosing all sorts of alopecia, starting with those that appear at birth, such as aplasia cutis congenita to those that appear in adolescence, such as androgenetic alopecia."

Dr. Piraccini noted that lanugo hair is produced at 16-20 weeks' gestation and is shed in utero and replaced by thicker hair at 32-36 weeks. "The speed of transition from vellus to intermediate and terminal hair varies from child to child," she said. "The scalp at birth presents with thin, intermediate, or thick hair."

In a dermoscopic evaluation of hair in 45 neonates during their first 30 days of life, Dr. Piraccini and colleagues found that 70% had low density hair while the remaining 30% had high density hair (Br J Dermatol 2013; 169:896-900). Two neonates presented a frontal-temporal pattern of hair loss. Trichoscopy revealed that nine neonates, all in the poor hair density group, had a particular hair shaft dermoscopic feature, characterized by the presence of widespread thin hair.

In some children, she continued, hair in the occipital area does not enter the telogen phase until after birth. These hairs remain on the scalp for 8-12 weeks and then fall out, resulting in neonatal occipital alopecia, which is the most common form of transient neonatal hair loss. Neonatal occipital alopecia is characterized by a band-like shape or oval alopecic patch with a sharp lower margin, but it often goes unnoticed by parents.

"It occurs with higher prevalence in infants born to mothers younger than age 34, in those with a non-cesarean birth, and in those with a gestational age greater than 37 weeks," Dr. Piraccini said. "There are different degrees of severity. On trichoscopy, the condition appears as thin regrowing hair. The outcome is totally benign, with normal hair growth within the first year of life."

Any aspect of alopecia in the occipital area in young children may be a sign of hair shaft disorders, which are characterized by increased hair fragility. "Trichoscopy is diagnostic," she said. "When applied to the hair you see monilethrix, a rare inherited disorder characterized by sparse, brittle hair that often breaks before reaching a few inches in length. As the child grows, the hair gradually acquires the characteristics it will have in adulthood. "It may remain thin and with a short anagen phase for several years, but acute shedding is rare," she said.

On trichoscopy, monilethrix appears as sparse, brittle hair that often breaks before reaching a few inches in length.

When an older child presents with increased hair shedding, the first exam to perform is the pull test. If it results in painless traction of several anagen hair without sheaths and with ragged cuticles, think about loose anagen hair syndrome. This condition affects females more than males, usually occurs between the ages of 2 and 5, and is characterized by a defective anchoring of the hair shaft to the hair follicle. The three clinical types of loose anagen hair syndrome are short, rough sparse hair; increased shedding; and areas of alopecia. The syndrome "tends to be inherited but spontaneously improves with aging," Dr. Piraccini said.

Alopecia areata, another common pediatric hair disorder, occurs in 20% of patients younger than 16 years of age and 9% of those with Down syndrome, and is associated with a family history of the condition. Young age at onset is a negative prognostic factor. "On trichoscopy, common features of alopecia areata are yellow dots, black dots, exclamation mark hairs, and broken hair," she said. "Trichoscopy can also help you distinguish acute from chronic alopecia areata. The risk of relapse is common, and psychological support is mandatory, because it is very stressful for children."

Another form of patchy alopecia, trichotillomania, occurs mainly in school-aged children and appears as irregular patches of alopecia with hairs broken at different lengths. "The pull test is negative because all telogen hairs have been pulled out by the patient," Dr. Piraccini said. "Parents often do not accept the diagnosis as they do not see the child touching his or her hair. It has a good prognosis."

Trichoscopic signs of trichotillomania include black dots, hair broken at different length, flame hair, clots of hair, and tulip hair. Treatment typically consists of psychological counseling and N-acetylcysteine 600-2,400 g/day.

Dr. Piraccini reported having no relevant financial disclosures.

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