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Nails Flashcards

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Dermatology Board Prep flashcards
1
Q

Eponychium

A

cuticle - thin strip of cornified epithelium that adheres to the nail at the edge of the proximal nail fold. Damage to the cuticle results in predisposition to inflammation of the nail fold –> disturb the underlying matrix and nail plate production

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2
Q

Lunula

A

white semi circle, junction between the matrix and the nail bed

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3
Q

Nail bed

A
  • underlying support structure - extends from the distal margin of the lunula to the onychodermal band. Has rugose rete ridges to enhance adhesion to the nail plate
  • The nail bed and nail plate lack a granular layer –> if there is a granular layer then that indicates pathology
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4
Q

Nail plate

A

packed onychocytes, continuous with the matrix

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5
Q

Vascular supply to the nail

A
  • 2 dorsolateral and 2 ventrolateral arteries that don’t have an internal elastic lamina - very tortuous –> ++ anastamosis
  • Cold environment –> constriction of vasculature, and AV anastamoses within glomus bodies maintain sufficient blood supply
  • Glomus bodies: encapsulated oval structures containing modified smooth muscle cells that dilate upon exposure to the cold –> prominent in subungual tissue which is the most common site of glomus tumours
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6
Q

Nerve supply to the nail

A
  • 2 dorsal and 2 ventral branches

- meissner and pacinian bodies (touch), type 1 fibres and temp all abundant in finger tips

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7
Q

Nail-patella syndrome:

A
  • LMX1B mutation, autosomal dominant
  • this encodes a transcription factor that regulates collagen synthesis
  • involves the thumb, and other fingers to a lesser extent –> nails are absent or hypoplastic, dystrophy usually more marked on the radial side of the digit
  • bone: absent or hypoplastic patellae, radial head dysplasia, iliac crest exostoses
  • X-ray: iliac horns on pelvic x-ray
  • 40% –> nephropathy –> 8% renal insufficiency
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8
Q

Clouston syndrome

A

form of ectodermal dysplasia due to gap junction gene mutation - GJB6 - encodes coonnexin –> thickened nails with onycholysis, hypotrichosis and palmoplantar keratoderma

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9
Q

Matrix function

A
  • onychocytes migrate upward and distally along an oblique axis during maturation and differentiation
  • proximal part of the matrix produces the dorsal nail plate. Abnormalities result in pitting, longitudinal ridging/splitting
  • distal matrix produces the ventral nail plate, abnormalities result in true leukonychia
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10
Q

Nail unit melanocytes

A
  • found in the nail matrix but not in the normal nail bed. foci of pigment in the nail bed that are separated from nail folds and matrix are not melanocytic in origin unless amelanotic melanoma or metastatic melanoa
    • more abundant in the distal matrix
    • main distribution in the nail plate is pigmented bands - longitudinal melanonychia
    • multiple streaks seen in those with darker skin, trauma or inflammation
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11
Q

Nail immune system

A
  • reduced expression of MHC class I and II antigens and decreased numbers of antigen presenting cells
  • immune privilege prevents over-reactivity to environmental antigens and makes vulnerable to infections and their oncogenic effects
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12
Q

Pachyonychia congenita

A

AD disorder encoding keratin 6a, 6b, 16 or 17 - these are in the nail bed, HF, sebaceous gland and palmoplantar –> leads to thickening of the nail plate (subungual hyperkeratosis), painful palmoderma keratomer, follicular keratoses, oral leukokeratosis and cysts

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13
Q

Beau’s line

A
  • transverse depressions of the nail plate surface from temporary interruption of the mitotic activity of the proximal nail matrix
  • depth indicates extent of damage, width indicates duration
  • most common causes: mechanical trauma, derm disease (eczema), if all fingernails –> systemic cause
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14
Q

Nail growth

A
  • fingernails grow faster than toenails: 2-3 mm/month, 1 mm/month
  • complete replacement of a nail requires 6-18 months (fingernails, toenails)
  • as the nail plate emerges from the proximal nail fold and progresses distally, it strictly adheres to the nail bed, approaches the tip of the digit and detaches from the nunderlying tissue forming the hyponychium
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15
Q

Nail signs - principle

A
  • Nail plate alterations –> due to matrix damage

- Nail plate detachment and/or uplifting arise from dysfunction of the hyponychium or nail bed

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16
Q

Onychomadesis

A
  • detachment of the nail plate from the proximal nail fold - due to severe insult that produces a complete arrest of nail matrix activity
  • similar causes to Beau’s line
  • it can also be from: hand, foot & mouth, scarlet fever, Kawasaki, horizontal orange-brown chromonychia
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17
Q

Nail pitting

A
  • punctate depressions
  • foci of abnormal keratinization of the proximal nail matrix which results in clusters of parakeratotic cells within the dorsal plate
  • over time, shedding of the parakeratotic cells leads to pits
  • Cause: psoriasis, alopecia areata, eczema
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18
Q

Onychorrhexis

A
  • longitudinal ridging and fissuring of the nail plate
  • depth of the ridges can vary
  • associated with nail thinning
  • causes: lichen planus, impaired vascular supply, trauma, tumours that compress the nail matrix
  • ddx: age related ridging of the nail plate
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19
Q

Trachyonychia/sand paper nails

A
  • Excessive longitudinal ridging –> nail plate roughness
  • Idiopathic, or can be from inflammatory skin disease - particularly alopecia areata, can be LP, eczema, psoriasis
  • fairly asymptomatic
  • Rx: systemic steroids and retinoids noted when treating alopecia areata or psoriasis, JAK inhibitor tofacitinib
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20
Q

True leukonychia

A
  • looks white because of the presence of parakeratotic cells within its ventral aspect
  • from nail matrix disturbance
  • Three types:
    • Punctate leukonychia - small opaque white spots that move distally with nail growth, and sometimes disappear before reaching the distal nail. Caused by trauma, see it in kids
    • Striate leukonychia - one or more transverse opaque white, parallel lines that migrate distally with growth. often due to matrix trauma secondary to manicures, trauma from shoes, also typical of Mees lines - white transverse bands seen in arsenic and thallium poisoning
    • Diffuse leukonychia - completely opaque. Rare, results from PLCD1 mutation or GJA1 (latter has keratoderma and hypotrichosis)
      • Bart-Pumphrey syndrome: deafness, knuckle pads, palmoplantar keratoderma, leukonychia, mutation in GJB2
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21
Q

Koilonychia

A
  • plate is thinned and flattened with upward eversion of its lateral and distal edges
  • kids - 2nd - 4th toes is physiologic and resolves spontaneously
  • adults - severe iron deficiency and systemic amyloidosis, manual laborers
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22
Q

Onycholysis

A
  • distal nail plate is detached from the nail bed and appears white due to air in the subungual space
  • if exogenous pigment present - yellow from fungi, green from pyocyanin
  • Causes: environmental trauma, psoriasis, infections, drugs (tetracyclines), metabolic/systemic (hyperthyroidism), tumours (subungual exostoses and SCC)
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23
Q

Subungual hyperkeratosis

A
  • thickened due to accumulation of subungual scales
  • results from excessive proliferation of keratinocytes in the nail bed and hyponychium
  • inflammatory disorders: psoriasis, contact dermatitis, distal subungual onychomycosis
24
Q

Apparent leukonychia

A
  • nail appears white due to abnormalities in colour of the nail bed, usually due to nail bed oedema
  • doesn’t move distally
  • fades with pressure
25
Q

Splinter haemorrhages

A
  • red-brown, purple-black thin longitudinal lines in the distal portion of the nail –> dermoscopy shows deep red to black colour with peripheral fading
  • causes: trauma, psoriasis, onychomycosis, medications, rarely endocarditis, vasculitis, trichinosis, antiphospholipid antibody syndrome
  • tuberous sclerosis: red comets –> short, longitudinal streaks of the nail with an enlarged distal end, partially blanchable
26
Q

Longitudinal melanonychia

A
  • melanin production by nail matrix melanocytes –> can be from melanocyte activation, or melanocyte hyperplasia found in a lentigo, naevus or melanoma
  • one or more longitudinal pigmented bands extending from the proximal nail fold to the distal margin
  • varies from light brown to black
  • multiple bands usually due to melanocyte activation
  • Causes
    • Melanocyte activation
      • Racial
      • Trauma
      • Drugs - psolarens, cancer chemo
      • Radiation
      • Pregnancy
      • Peutz-Jehger and Laugier-Hunziker
      • Addison
      • HIV
      • Post inflammatory
    • Non-melanocytic tumour
      • Bowens
      • Onychopapilloma
      • Onychomatricoma
    • Melanocyte herpplasia
      • Matrix lentigo
      • Matrix naevus
      • Matrix melanoma
  • Nail dermoscopy is tricky
  • Histopath remains the gold standard
27
Q

Green nail syndrome

A
  • Pseudomonas produces pyocyanin resulting in green-black nail discoloration –> most present in the subungual space
  • Risk factors: water exposure, nail trauma, onycholysis or paronychia
  • Rx: sodium hypochlorite 2% and can soak 5 minutes a day for 20-30 days
  • Underlying nail disorder also to be addressed
28
Q

Congenital malalignment of the great toenail

A
  • nail plate of the hallux is laterally deviated
  • possibly due to abnormality in ligament that connects the matrix to the periosteum
  • results in nail matrix damage, Beau’s lines and onychomadesis
  • bilateral often
  • most common cause of ingrown toenails
29
Q

Racquet thumb/brachyonychia

A
  • shortening of the distal phalanx
  • autosomal dominant
  • nail is short and abnormally wide
  • usually isolated finding
30
Q

Pachyonychia congenita

A
  • Mutated keratin gene
  • Nail abnormalities more marked in PC-K6a and PC-K16
  • Characteristic finding: thickened nail with an increased transverse curvature due to severe nail bed hyperkeratosis
  • Nails rae extremely hard and difficult to trim
  • Associated findings: hyperhidrosis, oral leukokeratosis, follicular hyperkeratosis, hoarseness, palmoplantar keratoderma, pain on ambulation
31
Q

Psoriatic nails

A
  • Associated with arthritis and enthesitis
  • Clinical: irregular pitting which may have scale, nail bed oil drops (salmon patch), onycholysis with an erythematous border
  • Can have other nail findings that are non-diagnostic: subungual hyperkeratosis, nail plate thickening and crumbling, etc
  • Ddx: onychomycosis, alopecia areata, trauma, Bazex syndrome
  • Rx: rarely responds to topicals, aggravated by the sun. Treatment options:
    • biologics/acitretin/immunosuppressant
    • avoid trauma
    • topical vitamin D analogue, etc
    • IL-steroid
32
Q

Acrodermatitis continua of hallopeau

A
  • Most patients, single digit involvement
  • recurrent episodes of acute painful inflammation with pustules around and under the nail plate
  • +/- onycholysis and scaling of the nail bed
  • associated with psoriasis
  • rarely, proximal spread –> acro-osteolysis of the distal phalanx
  • Ddx: onychomycosis, contact dermatitis, bacterial or viral
  • Rx: topical daivobet, IL-steroids, systemic acitretin, MTX, biologics
33
Q

Parakeratosis pustulosa

A
  • almost exclusively seen in kids
  • one digit - thumb or index
  • distal onycholysis, subungual hyperkeratosis, psoriasiform lesions
  • regresses spontaneously
  • topical steroids for rx
34
Q

Lichen planus nails

A
  • Nail thinning, longitudinal ridging (onychorrhexis) and fissuring, dorsal pterygium - due to scarring in the matrix, the proximal nail fold adheres to the nail bed
  • fissuring + atrophy –> ‘angel’s wings’
  • Can also have onycholysis, nail thickening, yellow discoloration
  • When isolated, very hard to establish diagnosis
  • Ddx: systemic amyloidosis, lichen striatus, dyskeratosis congenita, GVHD
  • Nail pterygium ddx: bullous diseases, digital ischaemia, psoriasis, basically anything that causes matrix scarring
  • RxL systemic steroids, IL-steroids
35
Q

Eczema nail signs

A
  • Acute –> vesicles and erythema of the proximal nail fold and hyponychium
  • Nail matrix –> irregular pitting and Beau’s lines, if severe onychomadesis
  • Chronic –> localizes to the hyponychium –> subungual hyperkeratosis, onycholysis, fissuring of the hyponychium, chronic paronychia
36
Q

Clubbing

A
  • 80% associated with pulmonary disease, think CVS, pulmonary
  • Causes by enlargement of the soft tissue of the distal digit
  • Nail plate is enlarged and excessively curved, with widening of the angle between the proximal nail fold and the nail plate to >180 degrees (Lovibond’s sign)
37
Q

Yellow nail syndrome

A
  • Uncommon
  • Pathogenesis unknown
  • Nails are thickened and transversely and longitudinally overcurved
  • Pale yellow to dark yellow-green
  • Onycholysis is frequently seen, and nail palte shedding
  • All nails involved
  • Associations: lymphoedema, respiratory tract involvement (bronchitis, bronchiectasis, etc)
  • Rx: not effective - vitamin E + pulse itraconazole or fluconazole
38
Q

Muehrke’s nails

A

hypoalbuminaemia and chemotherapy –> multiple transverse whitish bands paraellel to the lunula

39
Q

Half and half nails

A

apparent leukonychia affects the proximal half of the nail. Chronic renal disease –> haemodialysis

40
Q

Terry’s nails

A

common sign of liver cirrhosis, up to 80% of patients. Leukonychia affects the whole nail except for a 1-2 mm distal band

41
Q

Connective tissue disorder nail changes

A
  • Dermatomyositis and systemic sclerosis: roughness, haemorrhages, necrosis of the cuticles
  • Capillaroscopy: reduced capillary density with avascular areas
  • SLE: tortous capillaries
  • Ventral pterygium: attachment of distal nail plate to the hyponychium resulting in pain in nail trimming –> distinct of systemic sclerosis
42
Q

Chemotherapy nail changes

A

Beau’s lines, onychomadesis, fragility, onycholysis, paronychia, etc. Painful onycholysis with subungual haemorrhages - associated with taxanes

43
Q

EGFR inhibitor nail changes

A

paronychia with pyogenic granulomas, 1-3 months post starting treatment

44
Q

Retinoid nail changes

A

fragility, paronychia, periungual pyogenic granulomas

45
Q

ART drug nail changes

A

nail pigmentation, paronychia, pyogenic granulomas

46
Q

What causes photo-onycholysis

A

tetracyclines, taxanes, psoralens, PDT

47
Q

Acute paronychia

A
  • affected digit becomes swollen, red, painful, compression may produce purulent drainage
  • Commonly: bacteria (staph or strep), following minor trauma
  • Recurrent –> HSV
  • Treatment: drainage of abscess followed by systemic antibiotics
48
Q

Nail warts

A
  • Peri-ungual warts common in nail biters
  • Keratotic papules, and when localized to the proximal nail fold they produce periungual hyperkeratosis simulating a hyperketotic cuticle
  • Can lift up the nail plate
  • SCC can arise in or mimic verrucae
  • Rx: keratolytics, cryo, cantharadin, imiquimod, etc
49
Q

Chronic paronychia

A
  • usually from contact reaction to irritants or allergens
  • occupational –> food handlers
  • Inflammation of the proximal nail fold with erythema, oedema, absence of the cuticle
  • prolonged course, with superimposed, recurrent self-limited episodes of acute exacerbation
  • Rx: avoid water, topical steroids and imidazoles, antiseptics
50
Q

Idiopathic onycholysis

A
  • repetitive water immersion and irritant exposure –> affected nail is detached from the nail bed and appears white due to subungual space
  • rx: avoid water and chemicals
51
Q

Onychocryptosis - ingrown nails

A
  • lateral ingrowing in those with congenital malalignment –> can be quite painful
  • distal embedding - common complication of nail avulsion - nail plate growth is blocked by the hyponychium, which forms a distal rim
  • Rx: educate patient, remove embedded spicules, uplifting of the lateral nail plate with cotton or dental floss, grnaulation tissue may be reduced with topical steroids and antibiotics, chemical, laser or excisional surgical removal of the lateral matrix
  • Retronychia (where the proximal nail plate grows into the proximal nail fold) - surgical avulsion
52
Q

Main medication that causes onycholysis

A

Tetracyclines

53
Q

Main causes of koilonychia in adults

A

Severe iron deficiency

Systemic amyloidosis

54
Q

Cause of true leukonychia

A

Punctate: trauma, kids
Linear: trauma, adults
Diffuse: Bart Pumphrey - GJB2 mutation, deafness, PPK, knuckle pads

55
Q

Causes of onycholysis

A 
Environment: trauma, UV, exposures
Psoriasis 
Candida, HPV, dermatophyte 
Tetracyclines 
Hyperthyroidism 
Tumors

Derm (57 decks)

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