Hair and nails

Question 1

Hair types

Answer 1

• Lanugo hair: first hair in utero, lightly pigmented and thin
• Vellus hair: fine hairs that covers our bodies
• Terminal hair: coarse, pigmented hair seen in scalp, beard, pubic, axillary regions
• 100,000 hairs on scalp

Question 2

Hair anatomy

Answer 2

• From top to bottom
• Infundibulum: from surface to sebaceous gland duct
• Isthmus: from sebaceous gland duct to arrector pilli muscle
• Inferior segment: arrector pilli muscle to bottom of hair (bulb)
• From in to out: medulla, cortex, inner root sheath, outer root sheath
• Stem cells located in the bulge (where arrector pill connects), part of the external root sheath

Question 3

Hair growth cycle

Answer 3

• Anagen: growing phase (majority of hairs), lasts about 3 years
• Catagen: destruction phase (very small amount of hairs), lasts 3 weeks. Hairs will retract up to bulge in preparation for new anagen
• Telogen: resting phase (about 20%), lasts 3 months
• Anagen determines the length of a hair
• Bulge cells migrate out during telogen to begin new anagen phase
• In anagen the bulge cells self-renew outside the bulge

Question 4

Alopecia

Answer 4

-Loss of hair, can be generalized or localized, can be non-scarring (follicles preserved) or scarring (follicles destroyed, non-reversible)

Question 5

Types of alopecia areatas

Answer 5

• Alopecia areata: autoimmune (AI) disease against follicle, increased incidence in AD, downs. Localized loss, patchy
• Alopecia totalis: same mech, but total scalp loss
• Alopecia universalis: same mech, but total body loss
• Can see nail pitting (10%, more organized pitting), exclamation point hairs (diameter decreases closer to follicle)
• use topical steroids to Rx

Question 6

Androgenetic alopecia

Answer 6

• Patterned hair loss (most common hair loss in men)
• Polygenic inheritance, dihydrotestosterone (DHT)-dependent transition from large to small caliber hairs
• Age of onset (AOO): 12-40
• On the vertex and/or fronto-temporal regions of scalp
• Rx: topical solutions (minoxidil), hair transplants, finasteride (not for women)
• In women the pattern is diffuse through midscalp (christmas tree pattern)

Question 7

Telogen effluvium

Answer 7

• Diffuse shedding of hair (club-shaped hairs)
• Pull test abnormal (more than 6 is abnormal)
• Related to systemic insult to body, pregnancy
• Takes 6-12 months for hair density to return to normal

Question 8

Anagen effluvium

Answer 8

• Generalized and diffuse loss of 90% of scalp hair
• Occurs 1-2 mod after trigger (chemotherapeutics)
• Hair shafts thin when on chemo, breaks at surface (no bulb at end of hairs due to fracture)

Question 9

-Trichotillomania

Answer 9

• Hair pulling madness, impulse control disorder
• Varying lengths of hairs, do a scalp biopsy
• Increased catagen hairs, melanin within follicular canal
• Rx: behavior modification, SSRIs

Question 10

Traction alopecia

Answer 10

• Non-scarring alopecia that can become irreversible
• Due to chronic pulling forces
• Seen in some hairstyles (braids, rollers)

Question 11

Syphilitic alopecia

Answer 11

• Inflammatory, non-scarring alopecia
• Manifestation of secondary syphilis
• “moth-eaten” appearance, diffuse hair loss pattern

Question 12

Tinea capitis

Answer 12

• Dermatophyte (fungal) infection of the scalp and hair, mostly seen in children
• Patches of alopecia containing broken hairs w/ scale and erythema
• May have inflammatory rxn to dermatophytes, resulting in kerion (boggy pustular plaque)
• Rx is oral antifungal

Question 13

Dissecting cellulitis

Answer 13

• Mostly seen in adult black males, scarring alopecia
• Follicular occlusion triad: dissecting cellulitis, hidradentitis suppurativa, and acne conglobata
• Suppurative follicular nodules

Question 14

Acne keloidalis nuchae

Answer 14

• Mostly in black males, affects occipital scalp (back of neck), scarring alopecia
• Follicular papules/pustules that progress to firm nodules/plaque

Question 15

Discoid lupus erythematosus

Answer 15

• Scarring alopecia can be associated w/ systemic lupus

- PASTE symptoms

Question 16

Kerion

Answer 16

• Scarring or non-scarring alopecia
• Dermatophyte infection of scalp and hair follicle
• Large, boggy, erythematous plaque w/ papules, pustules, and crust

Question 17

Hirsutism

Answer 17

• Growth of androgen-dependent terminal hair in a women or child in a male pattern
• Can be cause by drugs, tumors, polycystic ovarian disease (POD), congenital adrenal hyperplasia
• POD: most common cause of ovarian hyperandogenism

Question 18

Hypertrichosis

Answer 18

• Excessive hair growth on any area of the body
• Can be localized or generalized, can be congenital or acquired
• Acquired hypertichosis languinosa: lanugo hair on face or body, may be paraneoplastic (due to malignancy), drugs, other IC conditions

Question 19

Nail anatomy

Answer 19

• Nail plate grows .1mm/day
• Plate comes from nail root (matrix, where nail stem cells are), which is under and behind the cuticle (surrounding skin)
• Thickened layer of skin surrounding the nails is eponychium
• Proximal and lateral nail folds
• Lunula: white crescent shaped area right in front of proximal nail fold

Question 20

Diseases of nails 1

Answer 20

• Clubbing of nails due to chronic hypoxia
• Psoriasis often shows oil spots and pitting (irregular) of the nails
• Koilonychia (spoon nails): due to Fe deficiency, anemia
• Terry’s nails: white proximal discoloration from cirrhosis (apparent leukonychia)
• Lindsay’s nails: half-half appearance from renal failure (apparent leukonychia)
• Muehrcke’s lines: paired, transverse white bands, from hypoalbuminemia (malnutrition, cirrhosis, apparent leukonychia)

Question 21

Diseases of nails 2

Answer 21

• Blue nails: wilson’s disease (Cu excess), gold rings in iris
• Green nails: from pseudomonas aeruginosa
• Proximal splinter hemorrhages: endocarditis, or trauma
• Onycomycosis/tinea unguium: dermatophyte infection, KOH prep to Dx
• Beau’s lines: transverse depression, result of temporary interruption of mitotic activity of nail matrix. Can be due to trauma, inflammation (eczema, psoriasis)
• True leukonychia (white discoloration, due to distal nail matrix damage): punctate (from trauma), striate (trauma), mew’s lines (striate due to arsenic and thallium poisoning)