Scalp Hair Characteristics in the Newborn Infant

Abnormal Hair Findings

Although a wide variety of normal hair pigmentation exists, a number of specific findings may warrant further investigation. The examiner should be alert for areas of hypopigmentation as well as abnormal hair quality, texture, patterning, or distribution.

Localized patches of hypopigmentation are usually inconsequential; however, a white forelock may indicate Waardenburg syndrome (Fig 7). This autosomal dominant syndrome is associated with iris pigmentation disturbances and severe, congenital bilateral cochlear deafness.^[3] Four types have been described.^[12] Fresh mutations are associated with advanced paternal age.^[3,12] Prompt hearing screening is indicated in suspect infants.

Albinism, an autosomal recessive trait, is a condition characterized by generalized hypopigmentation of the eyes, skin, and hair. Classic features include snow-white hair, pink eyes, and diffuse skin hypopigmentation. It can be detected at birth and is found worldwide in all races^[12] (Fig 8). Albinism is caused by either a failure of the melanocytes to produce melanin or decreased levels of the enzyme tryosinase resulting in decreased melanin synthesis.^[5] The melanocytes themselves can be normal in structure and function.^[12]

Chediak-Higashi syndrome is a lethal autosomal recessive disorder characterized by silvery sheen hair. It involves partial or incomplete albinism. Affected infants have recurrent bacterial infections attributable to abnormalities in cellular metabolism and chemotaxis.^[9,12]

Hair that is lighter than family members or that has a gray sheen may be the result of a generalized dilution of pigment. Genetic disorders that can present with hypopigmentation of scalp hair include the following:

Prader-Willi syndrome Piebaldism Ectodactyly-ectodermal dysplasia-clefting (EEC) syndrome Cross syndrome (oculo cerebral hypopigmentation) Chediak-Higashi syndrome

Piebaldism, an autosomal dominant disorder, is caused by defective proliferation and migration of melanocytes during fetal development.^[12] It is characterized by localized hypopigmentation of the scalp, trunk, upper arms, and legs. Demarcated patches of white skin and frontal scalp hair can be seen. The pigmentation on the hands and feet is normal (Fig 9).

A mixed pattern of hair pigmentation, normal hair color mixed with hypopigmented hair, is associated with Cross syndrome (also known as oculocerebral syndrome or hypopigmentation syndrome).^[19] There is a family history of consanguinity with this genetic disorder.

Light-colored hair can also indicate a nutritional deficiency or an inborn error of metabolism. In infants with phenylketonuria (PKU), excessive circulating phenylalanine inhibits the binding of tyrosine to tyrosinase and inhibits hair pigmentation.^[13] Caucasian infants with PKU typically have fair skin, blonde hair, and blue eyes; affected African American and Asian infants have hair lighter than siblings (Fig 10). A light hair color can also be seen in homocystinuria.^[3]

The terms hypotrichosis, hypotrichiasis, and diffuse alopecia often are used interchangeably to describe an infant with decreased hair. Typically, diffuse alopecia describes hair growth that is initially present but is later lost. Diffuse alopecia can indicate a genetic hair shaft abnormality. Isolated congenital alopecia can occur with and without other defects of the skin, hair, and nails.

Hypotrichosis is sometimes differentiated from alopecia as an abnormal deficiency of hair due to insufficient hair growth. Hypotrichosis may represent a total absence of hair follicles or it may be associated with a scattered, sparse hair pattern and a decreased number of small follicles that can be seen on biopsy. Both alopecia and hypotrichosis can be important, albeit subtle, features in many syndromes. These symptoms may present after the neonatal period.^[1]

Hypotrichosis with ectodermal dysplasia is an X-linked or autosomal recessive syndrome with variable hypoplasia of the hair follicles.^[2,3] The hair is hypopigmented and generally sparse. Hypotrichosis also can occur with ichthyoses.^[2] Acquired generalized alopecia can also be the result of a nutritional deficiency (zinc, vitamin B, biotinidase) or a metabolic deficiency (such as homocystinuria).^[9,10,15]

In contrast to generalized alopecia, some infants may manifest localized alopecia. Carefully note the location, distribution, and extent. Examine the scalp closely for a disruption in the scalp formation, such as the classic punch biopsy lesion of cutis aplasia. Although most lesions are isolated, cutis aplasia often is associated with trisomy 13 (Fig 11). Localized alopecia is associated with birth trauma from scalp monitors, forcep application, or vacuum extraction. Carefully examine the head for other associated findings, such as a cephalohematoma. Localized alopecia can also be the result of a nodular lesion of the scalp, a sebaceous nevus (Fig 12), or an epidermal nevus.^[2,7] Acquired localized alopecia can be the result of trauma from intravenous infiltration or extravasation or can occur with residual scars from infection. In older infants, alopecia confined to the occipit is related to typical cyclic hair loss at this stage.

Be alert for excessive hair formation. In diffuse hypertrichosis, there is excess development of hair follicles or a persistence of hair that usually disappears in the fetal period.^[5] Hair growth in excess of normal can be an isolated finding or seen as part of a syndrome.^[2] Genetic disorders that present with hypertrichosis include^[3]:

Cornelia de Lange syndrome (Fig 13) Coffin-Siris syndrome Leprechaunism Hurler syndrome (mucopolysaccharide storage disease) Trisomy 18

Hypertrichosis can be drug-induced. Drugs that induce hypertrichosis make vellus hairs grow larger and produce more pigmented terminal hair. In addition, these drugs can prolong the anagen phase of hair, resulting in longer hair fibers. Examples of drug-induced hypertrichosis are the fetal hydantoin syndrome^[3] and, occasionally, fetal alcohol syndrome.^[2] Postnatal corticosteroids and diazoxide are 2 additional drugs that can induce hypertrichosis.^[11]

Evaluate infants carefully for localized hypertrichosis. A tuft of hair, or a circular distribution of longer, darker hair, called the hair collar sign, may be present and signify underlying neural tissue abnormality.^[2] Examine the surrounding skin and tissues closely for an underlying nevus or other developmental abnormality, such as a cranial meningocele, encephalocele, or heterotopic meningeal or brain tissue.^[2] A congenital melanocytic nevus is a flat scalp lesion covered with dense, terminal hair that is darker, longer, and coarser than hair on the surrounding scalp^[2,7] (Fig 14).

Multiple hair whorls, an absent hair whorl, or an abnormally placed hair whorl (usually posteriorly) can be an indication of abnormal brain growth and mental retardation.^[3] After the newborn period, aberrant hair directional patterning, that is hair that lacks slope and sticks out straight or is unruly, may be associated with altered scalp shape, a lack of early fetal brain growth, or both.^[3]

A striking frontal upsweep may indicate a structurally abnormal brain or syndrome. Soft sparse scalp hair, frontal cowlicks and widow's peak hairline are noted in FG, or Kaveggia-Opitz syndrome. Other associated features include widely spaced eyes, low-set ears, a thin upper lip, and a full lower lip.^[15,17] Low frontal and low posterior hairlines are each associated with several syndromes, summarized in Table 3 . Low posterior hairlines are more consistently abnormal. Hair roots located below the neck crease, especially at the lateral edges, are seen in infants with syndromes involving a short or webbed neck.

Scalp hair that is brittle or fragile may indicate a hair shaft abnormality. Hair shaft abnormalities are seen in genetic and metabolic diseases; conditions associated with hair shaft abnormalities are summarized in Table 4 . These conditions present with hair that may appear beaded, flattened, and twisted; short, dull, or broken; or wooly and excessively kinky; or spangled, glistening, and uncombable.^[2,3,18] Be alert for other associated features and related syndromes. A careful clinical description of the hair is useful; microscopic examination of the hair shaft often is required to determine or confirm the diagnosis.^[12] Metabolic disorders, such as hypothyroidism, also are associated with dry, brittle, coarse hair.

Adv Neonatal Care. 2003;3(6) © 2003 W.B. Saunders

Cite this: Scalp Hair Characteristics in the Newborn Infant - Medscape - Dec 01, 2003.