Dermatology

Hair Shaft Disorders

Are You Confident of the Diagnosis?

What you should be alert for in the history

An alteration in hair shaft properties is clinically noticed as a change in strength (fragility, or inability to grow hair long), texture, appearance, and manageability. Thus, when a patient presents in the clinic with a chief complaint of “hair loss,” the possible causes may be vast, but a thoughtful and stepwise approach will quickly uncover clues that will lead the clinician to suspect a hair shaft disorder.

Patients with hair shaft disorders will often present with one of the following complaints:

--“My hair (or my child’s hair) does not grow long” or “My child has never had a haircut.”

--“My hair (or my child’s hair) has an unusual appearance and/or texture.”

--“My hair (or my child’s hair) suddenly started breaking.”

Directed questions that will help the clinician narrow the differential diagnosis include:

--When did the problem first start (has the problem been present since birth or was it acquired later in life)?

--Are there any problems with the skin, nails, teeth?

--How does the patient style or process the hair? Ask about brushing technique, frequency of shampooing, use of heat and chemicals.

--Do other family members have similar findings?

Characteristic findings on physical examination

--Evaluate for general appearance, length, luster, curl, and color.

--Note the distribution of the hair abnormality—diffuse or focal.

--Determine if there is hair breakage: For the close-up examination of individual hair shafts, a contrasting paper (white for dark hair, black for light hair) can be used to improve visibility. By placing the card near the scalp and behind the hair being examined, one can determine if there are blunt or broken hair distal tips that would suggest breakage. These broken hairs can be differentiated from newly growing hairs that have tapered or pointed distal tips. If fragility or breakage is suspected, it can be confirmed by performing a tug test . This test consists of holding the hair several centimeters from the hair tip then tugging at the ends. If the hair is fragile, short 2 to 4mm hair fragments will easily break off. When these small fragments of hair are mounted on a glass slide with a mounting medium and cover slip, characteristic changes of hair shaft disorders may be seen.

Expected results of diagnostic studies

The following list details the expected diagnostic findings of various hair shaft disorders on hair mount:

Acquired hair shaft disorder without increased fragility

--Pili bifurcati (Bifurcation of the hair shaft, with subsequent fusing)

--Pili gemini (Multiple hair shafts emanating from a single hair follicle)

Acquired hair shaft disorder with increased fragility

--Bubble hair (Air bubbles within hair shaft)

--Trichorrhexis nodosa (Brush-like ends in opposition; Figure 1)

Figure 1.

Trichorrhexis nodosa. Drawing by Susan D Anderson.

--Trichoptilosis (Split ends)

Congenital hair shaft disorders without increased fragility

--Uncombable hair syndrome (Longitudinal grooves may be seen with hair mount without mounting medium. Triangular or kidney bean shape on cross-section. Not an office procedure)

--Pili annulati (Alternating light and dark bands due to air cavities [Figure 2]. Seen with the naked eye by reflected light. In a hair mount, with transmitted light, air cavities appear dark when empty, and clear when fluid-filled.)

Figure 2.

Pili annulati. Drawing by Susan D Anderson.

--Woolly hair (No characteristic findings)

Congenital hair shaft disorders with increased fragility

--Trichothiodystrophy (Clean fracture through the cortex and the cuticle/trichoschisis. Ribboning, irregular outline of the hair shaft. Trichorrhexis-nodosa-like fractures, tiger tail: with polarizing microscopy—in position of darkness, crossed polarizers—bright and dark alternating domains.)

--Pili torti: Björnstad/Menkes (Closely grouped twists, seen in hair mount without mounting medium; Figure 3)

Figure 3.

Pili torti.

--Trichorrhexis invaginata: Netherton syndrome (Bamboo-like invaginations; Figure 4)

Figure 4.

Trichorrhexis invaginata. Drawing by Susan D Anderson.

--Monilethrix (Nodes alternating with constrictions [Figure 5]. Nodes have a normal diameter hair with a medulla, whereas constrictions lack a medulla and may show evidence of fracture)

Figure 5.

Monilethrix. Drawing by Susan D Anderson.

Although the clinical examination and hair mount are diagnostic in the majority of patients, additional tests may be required to secure a specific diagnosis. These tests include:

--fungal culture

--scalp biopsy

--polarizing or electron microscopy

--amino acid analysis

Diagnosis confirmation

The differential diagnosis of hair shaft disorders includes other disorders in which hair breakage may be seen. These include tinea capitis, trichotillomania, and alopecia areata. Although loose anagen hair syndrome is a disorder of hair anchorage and not the hair shaft, it is included in the differential diagnosis of hair shaft disorders since “abnormal hair growth” may be a presenting complaint. Patients with tinea capitis can be diagnosed with a hair mount and/or fungal culture. Patients with trichotillomania often have a “friar tuck” pattern of hair loss with extensive areas of hair breakage, as well as evidence of trauma of the scalp. A biopsy is often diagnostic. With active alopecia areata, patients have a positive pull test in which telogen hairs easily pull out. The hair shaft shows no abnormality and a biopsy is diagnostic showing a peribulbar inflammatory infiltrate. Patients with loose anagen hair syndrome also have hair that is easiy extractable. A hair mount shows a characteristic dystrophic anagen hair with a ruffled cuticle.

Who is at Risk for Developing this Disease?

Acquired hair shaft disorders can occur at any age, but are often related to hair care practices. Congenital hair shaft disorders may be noted at birth or in childhood (as the hair fails to grow or develops an abnormal appearance).

What is the Cause of the Disease?

Acquired disorder without increased fragility

--Pili bifurcati

Acquired disorders with increased fragility

Bubble hair:

--Etiology: Bubbles form within the hair cortex due to high temperatures from styling with blow dryers, flat irons, or curling irons.

--Pathophysiology: Bubbles in the hair lead to hair breakage and alterations in hair texture and manageability.

Trichorrexis nodosa

--Etiology: This hair fragility is thought to result from a combination of chemical, thermal and mechanical damage to the hair shaft, which then breaks easily with brushing.

--Pathophysiology: The “nodes” or fracture sites indicating damage to the outer hair shaft cuticle form along the hair shaft.

Trichoptilosis

--Etiology: Fraying of the distal ends of the hair shaft as a result of weathering of the hair (wear and tear). Most commonly seen in long hair.

--Pathophysiology: The cuticle is damaged, as a result the inner fibrils of the cortex are exposed

Congenital hair shaft disorders without increased fragility

Uncombable hair syndrome: AD or sporadic:

--Etiology: The molecular basis of the disorder/etiology is unknown.

--Pathophysiology: The irregular and changing shapes of the hair cross section prevent adjacent hairs from lying flat or forming locks, and this accounts for the stand away and spangled appearance. It has been suggested that a misshapen dermal papilla may alter the shape of the internal root sheath. Amino acid analysis and x-ray diffraction analysis of the hair is within normal limits.

Pili annulati: AD

--Etiology: The gene for pili annulati has been localized to the telomeric region of chromosome 12q20. Candidate genes include regulatory proteins involved in the normal formation or degradation of the basement membrane zone of the lamina densa and sublamina densa layers of the hair follicle.

--Pathophysiology: The bright bands correspond to abnormal air-filled cavities within the hair cortex. In a hair mount, these bright bands appear dark because transmitted light is not permitted to pass through.

Woolly hair: Sporadic or inherited

--Etiology: The molecular basis of the hair changes is unknown

--Pathophysiology: The term “woolly” stems from sheep’s wool; the cortex of wool fibers consists of two cell types, the orthocortex and paracortex, which have differing reactivity and expand unequally. This structural asymmetry causes the coiling and crimping of wool. Human hair may also at times have a woolly appearance even though it consists mainly of paracortex, and the explanation of the woolly appearance is incomplete.

Congenital hair shaft disorders with increased fragility

Trichothiodystrophy: autosomal recessive (AR)

--Etiology: cystine-deficient hair: cystine (sulfur-containing amino acid) content reduced to less than half of normal values. An inverse correlation has been noted between sulfur content and percent of hairs with shaft abnormalities (trichoschisis, trichorrhexis nodosa, or ribbon/twist). However there is no association between clinical disease severity and percent of abnormal hairs.

--Pathophysiology: nucleotide excision repair defect. The pathophysiologic changes in the hair that lead to the characteristic hair shaft changes are not fully understood.

Pili torti: Björnstad syndrome, AR/ Menkes syndrome, X-linked recessive

--Etiology: Alterations in the hair shaft may occur in the face of mitochondrial dysfunction and may be influenced by the presence of reactive oxygen species in both Bjornstad and Menkes.

--Pathophysiology: The twisting of the hair is likely due to irregularities in the inner root sheath, which may induce an uneven molding of the hair shaft

Trichorrhexis invaginata: Netherton syndrome AR

--Etiology: Genetic mutation of the SPINK5 gene, which is on chromosome 5q31-32 and encodes a serine protease inhibitor, LEKTI

--Pathophysiology: The role of serine proteases in the hair follicle is not fully described, but enzyme activity has been demonstrated at sites of keratinization, such as the inner root sheath. Thus, SPINK5 mutations may affect the integrity of the hair shaft as it is forming.

Monilethrix: autosomal dominant (AD) or AR

--Etiology: Keratin mutation of the type II basic hair keratins hHb1 and hHb6 on chromosome 12q13, which leads to alterations in the hair cortex (AD). An autosomal rescessive variant has been described due to desmoglein 4 mutation.

--Pathophysiology: Keratin defect leads to abnormal formation of the hair shaft.

Systemic Implications and Complications

Acquired disorder with no increased fragility: No associated systemic disorders.

Acquired disorders with increased fragility: No associated systemic disorders.

Congenital hair shaft disorders without increased fragility

--Uncombable hair syndrome 1497: See related chapter for full discussion of associated systemic disorders, including workup and management.

--Pili annulati: No known associated disorders

--Woolly hair: Woolly hair can occur as an isolated finding or in association with various genetic syndromes. These include palmar/plantar keratoderma, keratosis pilaris atrophicans faciei, Noonan’s syndrome, Carvajal syndrome, cardiofaciocutaneous syndrome, and Naxos disease. Woolly hair has also been described with cardiac defects and keratosis follicularis spinulosa decalvans. Thus, patients with woolly hair should have a full examination to evaluate for abnormalities such as facial dysmorphism, cutaneous abnormalities, cardiac abnormalities, and other findings in order to investigate if it is part of a larger genetic syndrome.

Congenital hair shaft disorders with increased fragility

--Trichothiodystrophy 1488: See related chapter for full discussion of associated systemic disorders, including workup and management.

--Pili torti: Björnstad syndrome is composed of pili torti, sensorineural hearing loss casued by a mutation in the BCS1L gene. For a full discussion of associated systemic disorders, see related chapters for information including workup and management.

--Trichorrhexis Invaginata /Netherton Syndrome: See related chapter for full discussion of associated systemic disorders, including workup and management.

--Monilethrix: Keratosis pilaris is always associated with monilethrix and is commonly on the upper back and shoulders. Other ectodermal features may include koilonychia, brittle nails, syndactyly, juvenile cataracts, decreased visual fields, and dental lesions.

Treatment Options

Acquired disorders with increased fragility

--Bubble hair: Cutting or growing out the affected hair, and then avoiding heat and using gentle hair care to prevent further formation of bubbles.

--Trichorrexis nodosa: Reduced use of heat, chemicals (hair dyes, permanents), and/or mechanical trauma such as brushing or rubbing. There is difficulty in defining “guidelines” for hair care in patients with hair shaft disorders since different hair types will have a highly variable tolerance for weathering and breakage. Patients are advised to practice gentle hair care and to minimize physical and chemical trauma to the hair. Full recovery may take 2 to 4 years.

Congenital hair shaft disorders without increased fragility

--Uncombable hair syndrome: Uncombable hair syndrome improves with age, without treatment, so that typically by adolescence, the dramatic hair changes are no longer as apparent. Advice to parents of children with uncombable hair syndrome is to treat the hair gently and to minimize friction on the hair. Smooth-tipped, wide-spaced combs or brushes should be used along with generous use of hair conditioners, detanglers, and silicone-based hair smootheners (typically sold under the category of anti-frizz products). Excessive brushing, heat, and chemicals should be avoided. Biotin supplementation (5mg/day) has been reported to improve the appearance and manageability of the hair in a few case reports. The mechanism by which such treatment may improve the hair is unclear, and ultrastructural studies of hair post-treatment have failed to show any ultrastructural changes. However, since biotin supplementation is safe and not costly, a trial may be considered in affected patients.

--Pili annulati: No treatment needed.

--Woolly hair: No treatment has been shown to help this condition. If straightening the hair with chemicals or heat is contemplated, care must be taken. Woolly hair nevus might darken and become less curly with time.

Congenital hair shaft disorders with increased fragility

--Trichothiodystrophy: No treatment has been shown to help the hair changes in this condition. Gentle hair care should be advised to minimize breakage.

--Pili torti: Björnstad/Menkes: No treatment has been shown to help the hair changes in these conditions. Gentle hair care should be advised to minimize breakage

--Trichorrhexis invaginata /Netherton Syndrome: There is no specific treatment for trichorrhexis invaginata, but the hair often improves with age and can resolve with time. Gentle hair care should be advised to minimize breakage.

--Monilethrix: Monilethrix may improve with puberty, with pregnancy, or with oral contraceptives, but usually it persists to some degree into adulthood. There have been case reports of monilethrix improving with oral retinoids. Patients are advised to protect the fragile hair from excessive combing, styling, or friction.

Optimal Therapeutic Approach for this Disease

All patients with acquired or congenital hair shaft disorders with increased fragility should be counseled on gentle hair care techniques. Choice of specific treatment, when available, is listed under treatment options.

Patient Management

Even when an appropriate diagnosis is made, patient acceptance of the diagnosis and adherence to gentle hair care advice is sometimes more difficult. When counseling patients with hair shaft disorders and increased fragility, demonstrating the blunt tips of the broken hairs or showing the broken fragments of hair from a tug test can be very convincing. In addition, a trip to the microscope to have the patient (or parent) view the hair can be of great value. Not only does this allow the patient (or parent) to visualize the cause of the hair problem, it frequently makes them a more receptive partner in a treatment recommendation that may involve altering long-time hair care routines. Photographic documentation and re-evaluation of the hair shaft can be done periodically (6 to 12 months) to demonstrate changes in hair and response to therapy (if one is available).

Unusual Clinical Scenarios to Consider in Patient Management

Retinoid therapy (isotretinoin, acitretin) has been associated with pili torti and acquired kinking of the hair. The precise mechanism(s) by which these shaft abnormalites occur remains to be determined. Acquired pili torti has also been described in pateints with anorexia nervosa.

What is the Evidence?

Gummer, CL. "Bubble hair: a cosmetic abnormality caused by brief, focal heating of damp hair fibres". Br J Dermatol. vol. 131. 1994. pp. 901-3.

(A detailed description of bubble hair and its cause.)

Boccaletti, V, Zendri, E, Giordano, G, Gnetti, L, De Panfilis, G. "Familial uncombable hair syndrome: Ultrastructural hair study and response to biotin". Pediatr Dermatol. vol. 8. 2007 Apr.

(Report of a family with four generations of uncombable hair syndrome. Although biotin supplementation improved appearance of hair, ultrastructural changes were not noted.

Giehl, KA, Ferguson, DJ, Dean, D, Chuang, YH, Allen, J, Berker, DA. "Alterations in the basement membrane zone in pili annulati hair follicles as demonstrated by electron microscopy and immunohistochemistry". Br J Dermatol. vol. 150. 2004. pp. 722-7.

(A detailed study of the ultrastructural changes in pili annulati)

Liang, C, Morris, A, Schlucker, S, Imoto, K, Price, VH, Menefee, E. "Structural and molecular hair abnormalities in trichothiodystrophy". J Invest Dermatol. vol. 126. 2006. pp. 2210-6.

(A study focusing on the hair changes in trichothiodystrophy)

Hinson, JT, Fantin, VR, Schonberger, J, Breivik, N, Siem, G, McDonough, B. "Missense mutations in the BCS1L gene as a cause of the Björnstad syndrome". N Engl J Med. vol. 356. 2007. pp. 809-19.

(Characterization of the gene defect and discussion of the importance of mitochondrial dysfunction in Björnstad syndrome)

Chavanas, S, Bodemer, C, Rochat, A, Hamel-Teillac, D, Ali, M, Irvine, ADS. "Mutations in SPINK5, encoding a serine protease inhibitor, cause Netherton syndrome". Nat Genet. vol. 25. 2000. pp. 141-2.

(Landmark article describing the genetic mutation in Nethertons.)

Karincaoglu, Y, Coskun, BK, Seyhan, ME, Bayram, N. "Monilethrix: improvement with acitretin". Am J Clin Dermatol. vol. 6. 2005. pp. 407-10.

(A case report of a 7-year-old girl, and a review of the literature)

Zlotogorski, A, Marek, D, Horev, L, Abu, A, Ben-Amitai, D, Gerad, L. "An autosomal recessive form of monilethrix is caused by mutations in DSG4: clinical overlap with localized autosomal recessive hypotrichosis". J Invest Dermatol. vol. 126. 2006. pp. 1292-6.

(The autosomal recessive type is contrasted with the defects seen in the more typical autosomal dominant type.)

Cheng, AS, Bayliss, SJ. "The genetics of hair shaft disorders". J Am Acad Dermatol. vol. 59. 2008. pp. 23-6.

(A review of the genetic basis of some of the hair shaft disorders)

Whiting, DA, Dy, LC. "Office diagnosis of hair shaft defects". Semin Cutan Med Surg. vol. 25. 2006. pp. 24-34.

(A practical review with an emphasis on diagnosis with hair mounts.)
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