16 - 89 - HAIR SHAFT DISORDERS

Question 1

most common hair shaft disorder associated with breakage

Answer 1

Trichorrhexis nodosa (TN)

Question 2

brittle, easily broken, and lusterless hair with white nodular swellings at irregular intervals along the hair shaft

Answer 2

Trichorrhexis nodosa

Patients with TN often complain of inability to grow hair past a certain length.

Question 3

acquired TN that usually presents as isolated patches that occurs from mechanical trauma secondary to a pruritic dermatosis.

Answer 3

Localized TN

Question 3

has primarily been observed in the **African American population **where the use of strong chemical and heat straightening treatments is more common

Answer 3

Proximal TN

Question 4

described in white and Asian populations and is associated with frequent shampoo use, brushing, and chemical treatments such as bleaching

Answer 4

Distal TN

Question 5

characteristic finding is a splayed paint brush bristle appearance

Answer 5

Trichorrhexis nodosa (TN)

caused by a breach in the cuticle leading to exposure of the fibers and increasing their susceptibility to fracture

Question 6

localized absence of cuticle that leads to exposure and a clean transverse fracture of the hair shaft

Answer 6

Trichoschisis

• associated with low-sulfur containing hair seen in trichothiodystrophy (TTD), but can also occur secondary to external trauma

Question 7

brittle, easily broken hair as well as short, brittle eyebrows and eyelashes

Answer 7

Trichoschisis

When trichoschisis occurs as part of TTD, possible clinical features include cutaneous findings such as lamellar ichthyosis, brittle nails, short stature, mental retardation, facial dysmorphisms, and gonadal dysgenesis

Question 8

Question 9

“tiger tail” hair with light and dark alternating bands is seen on polarized light microscopy

Answer 9

trichothiodystrophy (TTD)

This alternating pattern is related to irregular sulfur content of the hair, with lighter areas representing lower sulfur concentrations.

Question 10

characterized by hair shafts that are flattened and twisted 180 degrees along their long axis

Answer 10

Pili torti (“twisted hair”)

Question 11

Hair is brittle, dry, and appears spangled as a result of uneven light reflections

Answer 11

Pili torti (“twisted hair”)

• Fractures within the weak points of the twists result in shorter hair with increased fragility.
• Coarse hair or areas of alopecia are especially prevalent in the parietal and occipital areas.
• The scalp is the primary area affected, but eyebrows, eyelashes, and other body hairs may be involved.

Question 12

Question 12

hair shaft disorder seen in menkes syndrome

Answer 12

Pili torti, TN, trichoclasis, and trichoptilosis

Question 12

Menkes is an X-linked recessive disorder occurring secondary to a defect in what gene?

Answer 12

ATP7A gene encoding for a copper transporter

Diagnosis is made by low copper and ceruloplasmin levels.

Question 13

Netherton syndrome clinical triad

Answer 13

1. atopic diathesis,
2. ichthyosiform erythroderma,
3. trichorrhexis invaginata

Question 13

hair shaft disorders that may be seen with Netherton syndrome

Answer 13

trichorrhexis invaginata, pili torti and trichorrhexis nodosa

Question 13

commonly associated with Netherton syndrome and is characterized by invagination of the distal hair shaft into the proximal portion.

Answer 13

Trichorrhexis invaginata (bamboo hair)

• Hair has a dry, lusterless, brittle appearance with increased fragility.
• Areas of diffuse thinning with some instances of complete alopecia are present. Eyebrows and eyelashes are also affected.

Question 14

gene defect in Netherton Syndrome

Answer 14

SPINK5 gene

encodes an inhibitor of lymphoepithelial Kazal-type–related inhibitor (LEKTI).

Question 15

intussusception of the distal hair shaft into the proximal portion, which is soft and incompletely keratinized, leads to a “golf-tee” deformity

Answer 15

TRICHORRHEXIS INVAGINATA

Question 16

Typical beaded appearance of hair as seen under light microscopy

Answer 16

monilethrix

Question 16

Beaded hairs/ monilethrix emerge from keratotic follicular papules that are primarily seen in what area of the scalp?

Answer 16

occiput

Question 17

Light microscopy reveals a **pearl necklace appearance **with areas of knots and narrowing along the hair shaft.
Nonmedullated elliptical nodes can be seen at regular intervals, 0.7 to 1 mm apar

Answer 17

Monilethrix

Question 18

• Patients have unruly, frizzy, and dry hair that sticks out from scalp and is difficult to comb flat
• Hair is normally red-blond to light blond in color and has a spangled appearance.
• There is no increased fragility and hair is generally normal in both quantity and length.
• Eyebrows, eyelashes, and body hair are not affected.

Answer 18

UNCOMBABLE HAIR SYNDROME

Question 19

* Under closer analysis of hair cross-sections with electron microscopy, the affected hairs exhibit a** triangular or kidney shape with shallow longitudinal grooving. ** * It is thought that this l**ongitudinal grooving is responsible for the physical manifestation of the hair’s appearance.**

Answer 19

UNCOMBABLE HAIR SYNDROME

Question 20

* Hair is typically **sparse or completely absent **at birth with regrowth of coarse, wiry, and unruly hair during childhood. * Around puberty, **nonscarring hair loss **is again seen. * Pattern of hair loss may be similar to androgenic alopecia with thick hair scattered in thinning areas that are especially noted on vertex, parietal, and occipital regions. 4 * Total alopecia may be observed *** Scalp, eyebrows, eyelashes, secondary sexual hairs, and generalized body hair are affected. ** * Other cutaneous features associated with MUHH include **milia-like lesions **on the face as well as f**ollicular hyperkeratosis.**

Answer 20

Marie-Unna hereditary hypotrichosis (MUHH)

Question 21

Clinical examination reveals **multiple anagen hairs on pull test**

Answer 21

Marie-Unna hereditary hypotrichosis (MUHH)

Question 22

* characterized by** diffusely sparse, fine, short hairs. ** * **Follicular miniaturization **and n**oninflammatory alopecia **are characteristic of the disease.

Answer 22

Hereditary hypotrichosis simplex (HHS) i

Question 23

sporadic or inherited hair condition characterized by **hair that is loosely attached to the scalp.**

Answer 23

Loose anagen syndrome (LAS)

Question 24

Cuticles are also characteristically ruffled, baggy, twisted, and have a **floppy sock appearance.**

Answer 24

LOOSE ANAGEN SYNDROME

Question 25

* presents with **ringed hair **that is not usually associated with increased fragility. * characterized by **alternating light and dark bands.**

Answer 25

Pili annulati

Question 26

Alternating shiny and dull segments gives the hair an overall shiny, **speckled** appearance

Answer 26

Pili annulati ## Footnote lighter segments representing air-filled cavities

Question 27

electron microscopy shows a cobblestone appearance of the cuticle

Answer 27

Pili annulati

Question 28

Answer 28

Trichorrhexis nodosa (TN)

Question 29

Answer 29

Question 30

Answer 30

Pili torti

Question 31

Answer 31

Trichorrhexis invaginata

Question 32

Answer 32

Monilethrix

Question 33

Answer 33

Uncombable hair syndrome (pili trianguli et canaliculi; spun glass hair)

Question 34

Answer 34

Marie-Unna hereditary hypotrichosis

Question 35

Answer 35

Wooly hair

Question 36

Answer 36

Hereditary hypotrichosis simplex (HHS)

Question 37

Answer 37

Loose anagen syndrome (LAS)

Question 38

Answer 38

Pili annulati