Hair and Nail Disorders of Childhood

Dimitrios K Sotiriadis

Disclosures

Expert Rev Dermatol. 2008;3(6):677-690. 

In This Article

Hair Shaft Disorders

These abnormalities can be primary and hereditary or secondary, and are divided into those associated with hair breakage and those associated with unruly hair. Dermoscopy of hair and scalp (trichoscopy) is gaining popularity as a valuable tool in differential diagnosis of hair loss. This method allows viewing of the hair and scalp at ×20 to ×160 magnifications. Structures that can be visualized by trichoscopy include hair shafts of different types: vellus, terminal, micro-exclamation-mark type, monilethrix and trichorrhexis invaginata.[5,6]

Hair Shaft Disorders With Increased Fragility

For a list of hair shaft disorders with increased fragility see Box 1 .

Trichorrhexis Nodosa. Trichorrhexis nodosa is the most common defect of the hair shaft. Microscopically, affected hair develops a break in the cuticle with eventual separation and fraying of the exposed cortical fibers leading to a nodal swelling. The fibers then fracture and the shaft breaks.

Congenital trichorrhexis nodosa may be present at birth or appear within the first few months following birth. The occurrence of congenital trichorrhexis nodosa should lead to an investigation of an underlying metabolic disorder (argino-succinic aciduria and citrulinemia).

Patients with Menkes' syndrome, caused by a defect in copper efflux, and trichothiodystrophy, caused by a defect in the synthesis of the sulfure proteins integral to hair, have thin and brittle hair.

Acquired trichorrhexis nodosa is less common in childhood. Mechanical or chemical damage triggers the response.[7]

Trichoschisis: Trichothiodystrophy. Trichothiodystrophy (termed by Price et al.) is an autosomal recessive neuroectodermal disorder presenting with a low sulfur content in hair, caused by a mutation of a regulatory gene involved in the repair and transcription of DNA. This condition is characterized by brittle hair and trichoschisis. Polarized light examination shows light and dark bands of hair shafts ('tiger tail' pattern), possibly due to the irregular sulfur content. The hair cystine and sulfur content is less than 50% of normal in both the cuticle and cortex. An amino acid analysis of the hair shaft confirms the diagnosis.[8,9]

Pili Torti. Pili torti or 'twisting hair dystrophy' is seen as an isolated defect or in many different syndromes. Hereditary pili torti is usually autosomal dominant, potentially autosomal recessive or sporadic, is present at birth or develops over the first years of life. Patients have patchy alopecia with coarse stubble or longer broken hair. Hereditary pili torti improve after puberty.

Children with this condition should have early testing for hearing loss;[10] Bjornstad syndrome is an autosomal recessive disorder characterized by sensorineural hearing loss and pili torti.[10] In addition, in Crandall syndrome, which is probably inherited as an X-linked recessive trait, congenital hypotrichosis with pili torti is associated with sensorineural deafness and hypopituitarism.[11] Late-onset pili torti present after puberty and should be differentiated from patchy alopecia areata (AA).

Menkes Syndrome. Menkes syndrome is an X-linked recessive disorder of copper metabolism. The defective gene is ATP7A, and the affected child has depigmented brittle hair, pili torti or trichorrhexis nodosa, pale lax skin, severe psychomotor retardation, neurologic abnormalities and growth failure. Diagnosis is confirmed by a low serum level of copper and ceruloplasmin.

Copper-histidine administered immediately postpartum may ameliorate this condition.[12]

Trichorrhexis Invaginata (Bamboo Hair). Trichorrhexis invaginata is a distinctive hair shaft abnormality, characterized by the presence of nodose 'ball and socket'. If the shaft fractures, a golf tee-shaped distal end may occur. This deformity may be sporadic in normal hair or occur with other hair shaft abnormalities or, commonly, in association with ichtyosis linearis circumflexa in patients with Netherton's syndrome (NS). NS is a congenital ichthyosiform dermatosis caused by serine protease inhibitor Kazal-type 5 (SPINK5) mutations. Tissue kallikreins and lymphoepithelial Kazal-type-related inhibitor (SPINK5 product) may contribute to the balance of serine proteases/inhibitors in the skin and influence skin-barrier function and desquamation.[13]

Atopic manifestations are commonly present. The primary defect appears to be a disturbance of keratinization and the hair shafts of children are short, dry and fragile.[6,14]

Monilethrix. Monilethrix is a rare inherited (autosomal dominant) condition with variable expression. This disorder is caused by mutations in the genes for type II hair keratins hHb1 and hHb6 in the type II keratin gene cluster on chromosome 12q13. Both hHb1 and hHb6 are largely coexpressed in cortical trichocytes of the hair shaft.

Monilethrix is characterized by dryness, fragility and sparseness of the scale hair. Affected children usually have normal-appearing hair at birth, but within the first few months of life, this hair is replaced by brittle and fragile hair. Hair fibers have uniform elliptical nodes of normal thickness and intermittent constrictions. Microscopically, these elliptical nodes have a regular periodicity of 0.7-1 mm. The term 'regularly bended ribbon sign' has been suggested for describing the specific dermoscopic feature of monilethrix, that differentiates it from pseudomonilethrix and other causes of hair loss.[15]

Between nodes, the hair shaft usually fractures and hair rarely grows beyond 1-2 cm in length because of breakage. In most cases, the scalp is the only region involved and the disease is often associated with keratosis pilaris, physical retardation, cataract, syndactyly and nail/teeth abnormalities.

Monilethrix may improve spontaneously with age. Retinoids and topical minoxidil have been used in some cases.[16,17]

For a list of hair shaft disorders without increased fragility see Box 2 .

Uncombable Hair Syndrome. Uncombable hair syndrome is noted any time from infancy to puberty, and may be autosomal dominant or sporadic.

Clinically, hair is dry, silvery blond, shiny, slow growing, cannot be combed but not unduly fragile. On light microscopy, the hair shaft may appear quite normal but on scanning electron microscopy, the longitudinal grooves that make it abnormally rigid (triangular shape) - which accounts for the alternate term of 'pili triangulati et canaliculi' - can be seen. In any event, this abnormality in the hair shaft is not specific, but can be seen in normal hair and in several types of ectodermal dysplasia.

Generally, there is no effective treatment for the syndrome. However, some cases improve spontaneously.[18]

Woolly Hair. Presence of tightly curly hair on the scalp of non-Africans is a condition known as 'woolly hair'. It presents at birth or in infancy, being inherited (either as autosomal dominant or recessive trait). A rare association of woolly hair with familial keratosis follicularis spinulosa decalvans has recently been reported.[19]

Circumscribed area with curly hair is named 'woolly hair nevus'. Microscopic findings of the hair shaft in all forms are pili torti-like twisting, elliptical cross-sections and trichorrhexis nodosa.[20]

Marie Unna Hypotrichosis. Marie Unna hypotrichosis is a rare autosomal dominant condition, where hair is usually sparse or absent at birth. Wiry hair growth occurs in early childhood, and from late childhood scalp hair is lost in a pattern resembling androgenetic alopecia. Microscopically, hair shows irregular twisting, longitudinal ridging and cuticle peeling. Milia-like lesions on the face and diffuse follicular hyperkeratosis may be present. Marie Unna hypotrichosis maps to chromosome 8p21, close to the hairless gene.[20,21]

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