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Fitzpatrick's Dermatology, 9th Edition (Entrance Exam / Board Exam Prep) > 89: Hair Shaft Disorders > Flashcards

89: Hair Shaft Disorders Flashcards

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1
Q

What are the clinical features of Trichorrhexis Nodosa?

A

Trichorrhexis Nodosa is characterized by brittle, easily broken, and lusterless hair with white nodular swellings at irregular intervals along the hair shaft.

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2
Q

What are the primary and secondary causes of hair shaft disorders?

A
  • Primary disorder: Caused by a gene defect that changes the shape or composition of the hair shaft.
  • Secondary disorder: Caused by external factors leading to weakness and often breakage of the hair shaft.
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3
Q

What are the management strategies for Trichorrhexis Nodosa?

A

Management strategies include:

  1. Acquired Trichorrhexis Nodosa: Improves with removal of external trauma.
  2. Inherited Trichorrhexis Nodosa: Varying courses of management depending on individual cases.
  3. Removal of harsh chemical treatments for acquired cases.
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4
Q

What is the epidemiology of Trichorrhexis Nodosa?

A

Trichorrhexis Nodosa is the most common disorder associated with hair breakage, with varying prevalence among different populations:
- Proximal: More common in African Americans due to strong chemical and heat-straightening treatments.
- Distal: More common in white and Asian populations due to frequent shampoo use, brushing, and chemical treatments such as bleaching.

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5
Q

What are the differential diagnoses (DDx) for Trichorrhexis Nodosa?

A

Differential diagnoses for Trichorrhexis Nodosa include:

  • Alopecia areata
  • Androgenic alopecia
  • Monilethrix
  • Piedra
  • Seborrheic dermatitis
  • Telogen effluvium
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6
Q

What are the clinical features of Trichorrhexis Nodosa in African American populations?

A

In African American populations, Trichorrhexis Nodosa often presents as proximal TN due to strong chemical and heat-straightening treatments.

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7
Q

Describe the clinical features and diagnostic methods for Trichorrhexis Nodosa (TN).

A

Trichorrhexis Nodosa is characterized by brittle, easily broken, and lusterless hair with white nodular swellings at irregular intervals along the hair shaft. Diagnostic methods include light and electron microscopy, which reveal a splayed paintbrush bristle appearance caused by a breach in the cuticle leading to exposure of fibers and increased susceptibility to fracture.

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8
Q

What are the key diagnostic features of Trichorrhexis Nodosa under microscopy?

A

Under light and electron microscopy, Trichorrhexis Nodosa shows a splayed paintbrush bristle appearance caused by a breach in the cuticle, leading to exposure of fibers and increased susceptibility to fracture.

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9
Q

What are the characteristic findings associated with Trichothiodystrophy (TTD)?

A

TTD is characterized by:
- Brittle hair (trichoschisis)
- Short stature
- Mental retardation
- Facial dysmorphisms
- Gonadal dysgenesis
- Increased risk of respiratory tract infections

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10
Q

What are the major genes associated with Autosomal Recessive TTD?

A

The four major genes associated with Autosomal Recessive TTD are:
1. ERCC2 (XPD)
2. ERCC3 (XPB)
3. P8 (TTDA)
4. C7ORF11 (TTDN1 or MPLKIP)

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11
Q

What is the significance of polarized light microscopy in diagnosing TTD?

A

Polarized light microscopy reveals ‘tiger tail’ hair, which shows:
- Light and dark alternating bands
- Irregular sulfur content
- Lighter areas with lower sulfur concentration, indicating photosensitivity and hair shaft abnormalities.

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12
Q

What are the complications associated with TTD in children under 10 years old?

A

Children under 10 years old with TTD have:
- 20-fold higher rate of mortality compared to the general US population
- Complications include:
- Intellectual impairment (86%)
- Short stature (73%)
- Ocular abnormalities (51%)
- Ichthyosis (65%) at any point during their lifetime

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13
Q

What is the recommended management for acquired trichoschisis?

A

For acquired trichoschisis, it is recommended to:
- Reduce hair manipulation to improve the condition.
- TTD with systemic effects requires multidisciplinary care.

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14
Q

What are the photosensitive and nonphotosensitive types of TTD?

A

Photosensitive types of TTD involve defects in nucleotide excision repair and include mutations in XPD, XPB, and TTDA. Nonphotosensitive types are linked to TT DN1 mutations.

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15
Q

What are the systemic complications of TTD in children?

A

Children with TTD have a 20-fold higher mortality rate under 10 years of age and may experience intellectual impairment, short stature, ocular abnormalities, and ichthyosis.

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16
Q

What are the genetic and environmental causes of Trichoschisis and TTD?

A

Trichoschisis is caused by external trauma or secondary to TTD, while TTD is associated with genes involved in DNA repair and transcription, such as ERCC2 (XPD), ERCC3 (XPB), P8 (TTDA), and C7ORF11 (TTDN1 or MPLKIP). Photosensitive types are caused by defects in nucleotide excision repair, while nonphotosensitive types are linked to TT DN1 mutations.

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17
Q

What is the clinical significance of the ‘tiger tail’ hair pattern in TTD?

A

The ‘tiger tail’ hair pattern, seen under polarized light microscopy, is a diagnostic feature of TTD. It shows light and dark alternating bands due to irregular sulfur content, with lighter areas having lower sulfur concentration.

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18
Q

What are the management strategies for acquired Trichoschisis?

A

Acquired Trichoschisis improves with the removal of external trauma, such as reducing hair manipulation.

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19
Q

What are the systemic complications associated with TTD?

A

TTD is associated with intellectual impairment, short stature, ocular abnormalities, and ichthyosis. Children under 10 years with TTD have a 20-fold higher mortality rate compared to the general population.

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20
Q

What are the characteristics of Pili Torti and its common causes?

A

Pili Torti is characterized by flattened hair shafts that are twisted 180 degrees along their long axis. It typically appears within the first 3 years of life and primarily affects the scalp. Common causes include anorexia nervosa, severe malnutrition, and inflammatory scalp conditions. The hair appears brittle and dry, with weak points of twists leading to shorter hair and increased fragility. Areas of alopecia may occur, particularly in the parietal and occipital areas.

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21
Q

What is Trichorrhexis Invaginata and its associated syndrome?

A

Trichorrhexis Invaginata, also known as Bamboo Hair, is characterized by the invagination of the distal hair shaft into the proximal portion. It is associated with Netherton syndrome, which has an incidence of approximately 1 in 200,000 live births. This condition presents with dry, lusterless, brittle hair and increased fragility, affecting not only scalp hair but also eyebrows and eyelashes. Areas of diffuse thinning and instances of complete alopecia may be present.

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22
Q

What are the diagnostic methods for Netherton syndrome?

A

Diagnostic methods for Netherton syndrome include:

  1. Light microscopy: Shows intussusception of the distal hair shaft into the proximal portion, leading to a ‘golf tee’ deformity.
  2. Electron microscopy: Reveals defects in keratinization of the inner root sheath (IRS).
  3. Trichoscopy: Provides an accurate and quick diagnostic tool for identifying hair shaft abnormalities.
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23
Q

What are the clinical features and treatment options for Netherton syndrome?

A

Clinical features of Netherton syndrome include:
- Atopic diathesis (75%)
- Ichthyosiform erythroderma (at birth as a collodion baby or in early life as ichthyosis linearis circumflexa)
- Trichorrhexis invaginata (most common; can also have pili torti)

Treatment options include:
- Emollients
- Topical steroids
- Topical immunomodulators
- Systemic treatment: low dose corticosteroids, retinoids, and phototherapy.

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24
Q

What are the diagnostic features of Pili Torti under microscopy?

A

Light microscopy of Pili Torti shows flattened, twisted hair occurring at irregular intervals along the hair shaft. Scanning electron microscopy reveals a spiral pattern of the hair follicle.

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25
What are the systemic features of Netherton Syndrome?
Netherton Syndrome features include atopic diathesis, ichthyosiform erythroderma, and trichorrhexis invaginata.
26
What are the diagnostic features of Trichorrhexis Invaginata under trichoscopy?
Trichoscopy of Trichorrhexis Invaginata shows intussusception of the distal hair shaft into the proximal portion, creating a 'golf tee' deformity.
27
Explain the clinical presentation and management of Pili Torti.
Pili Torti is characterized by flattened hair shafts twisted 180 degrees along their long axis, leading to brittle, dry, and spangled hair. It primarily affects the scalp and is most common within the first three years of life. Management includes reducing mechanical trauma, as most cases improve spontaneously after puberty.
28
What are the diagnostic features of Trichorrhexis Invaginata (Bamboo Hair)?
Trichorrhexis Invaginata is diagnosed using light microscopy, which shows intussusception of the distal hair shaft into the proximal portion, creating a 'golf tee' deformity. Electron microscopy reveals defects in keratinization of the inner root sheath.
29
How does Menke syndrome relate to Pili Torti?
Menke syndrome, an X-linked recessive disorder caused by a defect in the ATP7A gene, is associated with Pili Torti. It leads to low copper and ceruloplasmin levels, resulting in brittle, twisted hair.
30
What are the systemic effects of Netherton Syndrome, and how is it managed?
Netherton Syndrome, associated with SPINK5 mutations, presents with atopic diathesis, ichthyosiform erythroderma, and trichorrhexis invaginata. Management includes emollients, topical steroids, immunomodulators, and systemic treatments like low-dose corticosteroids and retinoids.
31
What are the clinical features of Pili Torti in postpubertal cases?
In postpubertal cases, Pili Torti presents with darker hair that is brittle, dry, and spangled due to uneven light reflections.
32
What are the key clinical features of Monilethrix?
- **Autosomal dominant inheritance** (KRT81, KRT83, KRT86) - Short, dry, lusterless hair with a **beaded appearance** - Hair emerges from **keratotic follicular papules**, primarily seen in the occiput - Eyebrows, eyelashes, and body hair may be affected in more severe forms - Light microscopy shows a **'pearl necklace' appearance** with areas of knots and narrowing along the hair shaft.
33
What is the typical management for Uncombable Hair Syndrome?
- **Biotin supplementation** is recommended; however, no specific treatment has been identified and is generally not necessary. - Hair typically improves with age and most cases resolve after puberty.
34
What are the associated disorders with Marie Unna Hereditary Hypotrichosis (MUHH)?
- Various forms of **ectodermal dysplasia** such as: - Bork syndrome - Multiple epiphyseal dysplasia - Type I NF - No known treatment for MUHH.
35
What are the associated conditions with Uncombable Hair Syndrome?
Uncombable Hair Syndrome is associated with ectodermal dysplasia, Bork syndrome, multiple epiphyseal dysplasia, and type I neurofibromatosis.
36
What are the associated abnormalities with Monilethrix?
Monilethrix may have associated cutaneous, renal, and dental abnormalities, including keratosis pilaris, koilonychia, cataracts, teeth abnormalities, syndactyly, and mental disability.
37
What are the diagnostic features of Uncombable Hair Syndrome under electron microscopy?
Electron microscopy of Uncombable Hair Syndrome shows a triangular or kidney-shaped cross-sectional appearance with longitudinal grooving.
38
What are the management strategies for Monilethrix?
Management of Monilethrix includes oral retinoids, topical minoxidil, and reducing mechanical trauma.
39
What are the clinical features of Uncombable Hair Syndrome in acquired forms?
Acquired forms of Uncombable Hair Syndrome are common in dark, curly-haired individuals and occur later in life.
40
What are the diagnostic features of Monilethrix under trichoscopy?
Trichoscopy of Monilethrix reveals dilated nodes and constricted internodes, giving a 'pearl necklace' appearance.
41
What are the genetic mutations associated with Monilethrix, and how is it diagnosed?
Monilethrix is associated with autosomal dominant mutations in type II hair keratins, including KRT81, KRT83, and KRT86, and rarely with autosomal recessive DSG4 mutations. Diagnosis involves light microscopy, which shows a 'pearl necklace' appearance with areas of knots and narrowing along the hair shaft.
42
Describe the clinical features and inheritance pattern of Uncombable Hair Syndrome.
Uncombable Hair Syndrome is characterized by unruly, frizzy, dry hair that is difficult to comb flat. It is most common within the first few months of life and can occur up to 12 years of age. The majority of cases are autosomal dominant, with some autosomal recessive variants involving PADI3, TGM3, and TCHH genes.
43
What is the genetic basis of wooly hair and its inheritance patterns?
Wooly hair can be caused by both **autosomal dominant** (KRT71) and **autosomal recessive** forms. The autosomal recessive types include: - **Type I:** P2RY5 or LPAR6 - **Type II:** LIPH It is primarily seen in white and Asian individuals and appears during childhood or adolescence.
44
What are the clinical features associated with wooly hair?
Clinical features of wooly hair include: - **Tight curls** with an average diameter of 0.5 cm - **Brittle hair** with no increased fragility - Possible presence of **trichorrhexis nodosa** - Hair may be shorter due to a **briefer anagen phase** Light microscopy and scalp biopsy are typically normal.
45
What are the variants associated with wooly hair?
Variants associated with wooly hair include: 1. **Hereditary wooly hair (AD)** - with ocular anomalies 2. **Familial wooly hair (AR)** - concomitantly with palmoplantar hyperkeratosis and cardiac anomalies (Naxos and Carvajal syndrome) 3. **Symmetrical circumscribed allotrichia** 4. **Wooly hair nevus** - accompanied by melanocytic or epidermal abnormalities.
46
What are the variants associated with wooly hair?
Variants associated with wooly hair include: 1. Hereditary wooly hair (AD) - with ocular anomalies 2. Familial wooly hair (AR) - concomitantly with palmoplantar hyperkeratosis and cardiac anomalies (Naxos and Carvajal syndrome) 3. Symmetrical circumscribed allotrichia 4. Wooly hair nevus - accompanied by melanocytic or epidermal nevi with delayed bone growth, periodontal changes, and developmental delay.
47
What is the clinical significance of wooly hair appearance over time?
Wooly hair appearance is most pronounced in childhood and becomes significantly less evident in adulthood. No treatment has been established for wooly hair, and harsh chemical and physical injury should be avoided.
48
What are the clinical features of Marie-Unna Hereditary Hypotrichosis (MUHH) during childhood?
During childhood, MUHH presents with sparse or absent hair that may regrow as coarse, wiry, and unruly.
49
What are the genetic mutations associated with Wooly Hair?
Wooly Hair is associated with autosomal dominant mutations in KRT71 and autosomal recessive mutations in P2RY5 (LPAR6) and LIPH.
50
What are the associated conditions with Wooly Hair?
Wooly Hair is associated with Naxos disease, Carvajal syndrome, Noonan syndrome, cardio-faciocutaneous syndrome, and keratosis pilaris.
51
What are the diagnostic features of Wooly Hair under light microscopy?
Light microscopy and scalp biopsy of Wooly Hair are typically normal.
52
What are the clinical features and genetic basis of Marie-Unna Hereditary Hypotrichosis (MUHH)?
MUHH presents with sparse or absent hair, which may regrow as coarse, wiry, and unruly in childhood but may be lost again at puberty. It is caused by a heterozygous mutation in the U2HR gene, which inhibits the HR gene on chromosome 8p21.
53
What are the distinguishing features of Wooly Hair, and what syndromes is it associated with?
Wooly Hair is characterized by unruly, tightly coiled hair with an average curl diameter of 0.5 cm. It is associated with syndromes like Naxos disease (plakoglobin mutation) and Carvajal syndrome (desmoplakin defect), which involve cardiac anomalies and palmoplantar keratoderma.
54
What are the clinical features of Hereditary Hypotrichosis Simplex (HHS)?
- Diffusely sparse, fine, short hairs - Follicular miniaturization and inflammatory alopecia are characteristic of the disease - Body hair may be involved.
55
What is the epidemiology of Loose Anagen Syndrome (LAS)?
- Occurs in children between 2 and 6 years - 6:1 F:M ratio - Diagnosis should be considered in all presentations with scant, thinning hair.
56
What are the diagnostic features of Loose Anagen Syndrome (LAS)?
- Pull test: increased anagen hairs (3-10 hairs) - Light microscopy: anagen hairs with distorted bulbs, cuticles have a 'floppy sock' appearance - Trichogram: 70% anagen hairs.
57
What is the clinical course of Loose Anagen Syndrome (LAS)?
- Resolves with age; when LAS presents late, hair loss is more likely to be persistent.
58
What are the management options for Loose Anagen Syndrome (LAS)?
- Gentle hair care - 5% minoxidil - Biotin: no evidence of benefit.
59
What are the clinical features of Pili Annulati?
- Characterized by alternating light and dark bands; hair has a 'speckled' appearance - The scalp is the primary site affected with involvement of 20% to 80% of hair and a decrease in number of bands distally.
60
What is the etiology of Pili Annulati?
- Can be sporadic or inherited (autosomal dominant) - Associated with a single defect on chromosome 12q24.33 - If associated with hair fragility: elevated lysine and decreased cysteine content.
61
What are the diagnostic features of Pili Annulati?
- Trichoscopy: alternating white and dark bands; white segments with air-filled cavities - Light microscopy: reversal of white and dark bands due to air cavities scattering light - Electron microscopy: shows pseudopili annulati, fragmented medulla, bubble hair, pseudopili torti.
62
What is the clinical course of Pili Annulati?
- Lifelong condition - Clinical features become more prominent with age; course is benign.
63
What are the management options for Pili Annulati?
- Gentle hair care practices - No specific treatment available.
64
What are the three phenotypes of Loose Anagen Syndrome (LAS)?
The three phenotypes of LAS are: Type A - sparse, dull, unruly hair that doesn’t grow long; Type B - diffuse or patchy unruly hair; Type C - adults with excessive shedding.
65
What are the clinical features of Pili Annulati?
Pili Annulati is characterized by alternating light and dark bands, giving a speckled appearance. It primarily affects the scalp, with 20-80% of hair involved.
66
What are the diagnostic features of Loose Anagen Syndrome under light microscopy?
Light microscopy of Loose Anagen Syndrome shows anagen hairs with distorted bulbs and cuticles that have a 'floppy sock' appearance.
67
What are the associated conditions with Pili Annulati?
Pili Annulati has been observed in patients with wooly hair and alopecia areata.
68
Explain the clinical course and management of Loose Anagen Syndrome (LAS).
Loose Anagen Syndrome presents with diffusely sparse hair that is easily pulled from the scalp without pain. It resolves with age, but late presentations may lead to persistent hair loss. Management includes gentle hair care and 5% minoxidil.
69
What are the diagnostic features of Pili Annulati?
Pili Annulati is diagnosed by trichoscopy, which shows alternating white and dark bands due to air-filled cavities scattering light. Light microscopy reveals a reversal of white and dark bands, while electron microscopy shows a cobblestone appearance of the cuticle.
70
What are the clinical features and inheritance patterns of Hereditary Hypotrichosis Simplex (HHS)?
HHS presents with diffusely sparse, fine, short hairs and follicular miniaturization. It has four autosomal dominant subtypes (HYPT1-4) and six autosomal recessive subtypes (HYPT5-10).
71
What is the appearance of hair in Trichorrhexis Nodosa?
Splayed paint brush bristle appearance.
72
What are the characteristics of Pili torti?
Twisted hair.
73
What does Trichorrhexis Invaginata resemble?
Bamboo hair, golf tee deformity.
74
What is the appearance associated with Monilethrix?
Beaded hair, pearl necklace appearance.
75
What is the hair appearance in Uncombable Hair Syndrome?
Spun glass hair, triangular/kidney shaped appearance.
76
What does Pili Annulati look like?
Ringed hair, speckled appearance with alternating white and dark bands, shiny hair.
77
What is the clinical significance of Wooly Hair?
Tightly coiled hair associated with Naxos and Carvajal syndromes.
78
What is the appearance of hair in Loose Anagen Syndrome?
Floppy sock appearance.
79
What are the clinical features associated with Menkes syndrome?
- Hypotonia - Failure to thrive - Seizures - Developmental delay - Pale skin and sparse, coarse, lighter-colored hair.
80
What is the inheritance pattern of Netherton syndrome and its associated gene defect?
- Inheritance Pattern: Autosomal recessive - Gene Defect: SPINK5 serine protease inhibitor, Kaal type 5 gene.
81
What are the clinical features of Pili Torti as seen in various syndromes?
- Sensorineural deafness - Hypopituitarism - Congenital hypotrichosis - Alopecia areata - Decreased beard and body hair.
82
What are the clinical features of Trichothiodystrophy (TTD)?
- Severe forms are associated with developmental delays, short stature, skin abnormalities, and fragile hair - Increased risk for cancer due to DNA repair defects.
83
What is the inheritance pattern and gene defect associated with Wooly hair syndrome?
- Inheritance Pattern: Autosomal dominant - Gene Defect: KRT17 keratin 17 gene.
84
What are the clinical features of Goltz syndrome (focal dermal hypoplasia)?
- Facial abnormalities (asymmetry of the face, narrow nasal bridge) - Skeletal features (lateral, claw hands, syndactyly) - Congenital impairments (CNS features, microcephaly) - Colobomas, malformation of ears, and dental issues.
85
What are the clinical features of BIDS (Amish brittle hair syndrome)?
- Brittle hair - Brittle nails - Intellectual deficiency - Decreased fertility - Short stature - Ataxia - Seizures - Microcephaly.
86
What is the inheritance pattern of HYPT1 subtype of hypotrichosis?
- Inheritance Pattern: Autosomal dominant - Gene Defect/Location: Heterozygous mutation in APCD1 on Chromosome 18.
87
What are the clinical features associated with Sabinas syndrome?
- Brittle hair - Brittle nails - Intellectual deficiency - Decreased fertility - Ocular symptoms such as retinopathy.
88
What is the gene defect associated with HYPT6 subtype of hypotrichosis?
- Gene Defect/Location: Homozygous or compound heterozygous mutation in DS64 on Chromosome 18.
89
What are the clinical features of PIBIDS?
- Brittle hair - Brittle nails - Intellectual deficiency - Decreased fertility - Short stature - Ichthyosis - Photosensitivity.
90
What are the clinical manifestations of Trichorrhexis nodosa (TN)?
Brittle, lustrous hair with white nodular swellings along the hair shaft.
91
What diagnostic methods are used for Trichorrhexis nodosa (TN)?
Light and electron microscopy; displays painted brush bristle appearance.
92
What is the management approach for Trichorrhexis nodosa (TN)?
Acquired TN may improve with removal of external trauma; inherited TN may have varying courses.
93
What are the clinical manifestations of Trichoschisis and trichotillodytrophy (TTD)?
Brittle, easily broken hair with short, brittle eyebrows and eyelashes; clinical and cutaneous features of TTD may accompany hair findings.
94
What diagnostic methods are used for Trichoschisis and trichotillodytrophy (TTD)?
Polarized light microscopy shows 'large tail' hair; genetic testing and amino acid analysis of the hair shaft are also performed.
95
What is the management approach for Trichoschisis and trichotillodytrophy (TTD)?
Acquired trichoschisis improves with removal of external trauma; TTD requires multidisciplinary care depending on the clinical phenotype.
96
What are the clinical manifestations of Pili torti?
Brittle, dry, and spangled form uneven light reflections.
97
What diagnostic methods are used for Pili torti?
Light microscopy reveals flattened, twisted hair occurring at irregular intervals along the hair shaft.
98
What is the management approach for Pili torti?
Most cases show spontaneous improvement after puberty; mechanical trauma should be reduced.
99
What is the inheritance pattern of Trichorrhexis Invaginata and its clinical manifestation?
Trichorrhexis Invaginata is inherited in an autosomal recessive manner. Clinically, it presents with lusterless hair and beaded appearance due to keratotic follicular papules affecting eyebrows, eyelashes, and body hair.
100
What are the clinical features and management options for Unruly Hair syndrome?
Unruly Hair syndrome is characterized by uncombable hair that is fragile and may not be easily styled. It usually resolves after puberty. Management may include biotin supplementation, which can be helpful, although treatment is generally not necessary.
101
Describe the characteristics and diagnosis of Marie-Unna hereditary hypotrichosis.
Marie-Unna hereditary hypotrichosis is inherited in an autosomal dominant manner. It presents with sparse, brittle hair that may recur at puberty. Diagnosis can be made through pull test and scalp biopsy, which shows reduced number of follicles and evidence of fibroids.
102
What are the clinical features of Wooly Hair syndrome and its related conditions?
Wooly Hair syndrome is characterized by tight curls with an average diameter of 0.5 cm and may present with brittle hair. Diagnosis involves light microscopy and scalp biopsy. Related conditions include Hereditary wooly hair and Naxos disease.
103
What is the inheritance pattern and clinical presentation of Hereditary hypotrichosis simplex?
Hereditary hypotrichosis simplex is inherited in an autosomal dominant manner. Clinically, it presents with diffuse, sparse hair and may involve focal areas of defect in the cuticle. Complete baldness may occur by age 30.
104
What are the characteristics of Loose Anagen Syndrome (LAS)?
- Sporadic and inherited condition (autosomal dominant, KGF gene) - Hair is diffusely sparse and easily pulled from the scalp without pain. - Individuals may need a haircut, but there is no increased hair fragility. - LAS has 3 phenotypes. - Pull test: increased anagen hairs. - Light microscopy: anagen hairs with distorted bulbs, cuticles have a 'Trophy sock' appearance. - Trichogram: 70% anagen hairs. - Resolves with age; when LAS presents hair, it is less likely to be persistent.
105
What are the key features of Pili Annulati?
- Sporadic or inherited condition (autosomal dominant, single defect on chromosome 12q24.33). - Characterized by alternating light and dark bands; hair has a 'speckled' appearance. - Trichoscopy: alternating white and dark bands; light microscopy shows a cobblestone appearance of the cuticle. - Clinical features become more prominent with age; course is benign. - Gentle hair care practices, no specific treatment available.

Fitzpatrick's Dermatology, 9th Edition (Entrance Exam / Board Exam Prep) (213 decks)

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