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13. The Skin > 13.8 Nail Diseases > Flashcards

13.8 Nail Diseases Flashcards

1
Q

Def Nail dystrophy

A

Any abnormality of the fingernail(s) and/or toenail(s) including abnormalities of:
- Shape
- Colour
- Texture
- Growth

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2
Q

Def Onychomycosis

A
  • Any fungal infection of the nails. (Any fungal infec of nail)
  • This includes dermatophyte and non-dermatophyte infections.
  • Examples: Fusarium spp., Aspergillus spp., Candida spp.
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3
Q

Def Tinea unguium

A
  • Dermatophytic onychomycosis (i.e., dermatophyte infection of the nails)
  • Accounts for about 90% of onychomycosis
  • Examples: T. rubrum, T. interdigitale, T. tonsurans, and E. floccosum.
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4
Q

Predisposing factors

A

Local factors
- Chronic tinea pedis (athletes foot)
- Chronic paronychia (→ candida spp)
- Trauma or other nail disorders

Host factors
- Poorly controlled diabetes mellitus
- Immunosuppressione.g.,HIV
- Peripheral vascular disease (decreased blood flow to the feet)

Environment
- Occlusive footwear
- Sweating

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5
Q

How do fungi enter the nail?

A
  1. distal/lateral subungual (most common)
    - invasion via the hyponychium
  2. superficial white
    - direct penetration into the dorsal surface of the nail plate
  3. proximal subungual (rare)
    - invasion under the proximal nail fold
    - usually immunocompromised hosts
  4. mixed pattern
    - ≥2 of the above patterns in the same nail
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6
Q

How do fungi affect the nails?

A

Cause destruction of keratin in the nail
- Subungual hyperkeratosis (keratin debris under the nail plate)
- Crumbling
- Thickening
- Discolouration
- Nail plate destruction

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7
Q

What is paronychia?

A
  • Inflammation of the nailfold (usually proximal)
  • Can be divided into acute and chronic forms
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8
Q

Importance of the cuticle

A

The cuticle (eponychium) acts as a seal to prevent irritants and pathogens entering beneath the proximal nailfold.

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9
Q

Acute paronychai
Mechanism
Pathogens

A

Nail biting or sucking
Manicures
Ingrown toenails
Medications e.g. oral retinoids
⬇️
Minor trauma
⬇️
Post of entry for infections

Pathogens
- Usually caused by bacterial infection
• Staphylococcus aureus or Streptococcus pyogenes
- Recurrent acute paronychia
• Herpes simplex virus (‘herpetic whitlow’)

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10
Q

Chronic paronychia
Mechanism
Pathogens

A

Occupations that involve wet work, irritant contact dermatitis of hands
⬇️
Disruption of cuticle
⬇️
Irritants enter (esp. H20) causing inflammation at proximal nailfold

Pathogens
- Chronic paronychia is caused by irritants (esp H20) and is not primarily an infection.
- However, secondary infections do occur, typically Candida (e.g., Candida albicans).

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11
Q

Nail dystrophy
Causes

A
  • Infections (see lecture on fungal nail infections)
  • Benign or malignant growths
  • Cysts
  • Systemic diseases
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12
Q

Nail dystrophy: asymmetric involvement

A
  • Think about an external cause e.g., dermatophyte infection
  • If only 1 nail involved, think about a local problem e.g., cyst or tumour
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13
Q

Nail dystrophy: symmetric involvement

A

Think about an internal cause i.e., systemic diseases

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14
Q

What is clubbing?

A
  • Enlargement of the soft tissue of the digits.
  • Bulbous appearance
  • Enlarged, curved nail plate
  • Angle between proximal nailfold and nail plate widened to >180 degrees
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15
Q

Clubbing
Associated conditions (congenital & Acquired)

A

Congenital
- Cystic fibrosis
- Congenital cyanotic heart disease

Acquired
- Bronchopulmonary disease
• Neoplasms (primary or metastatic cancers, pleural tumors)
• Chronic infections (abscesses of the lungs, tuberculosis)
• Bronchiectasis
• Pulmonary fibrosis
• Sarcoidosis
- Cardiovascular disease e.g., bacterial endocarditis
- Gastro-intestinal disease e.g., chronic active hepatitis, IBD
- Endocrine disease e.g., hyperthyroidism
- Other

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16
Q

Clubbing
Mechanism

A

MECHANISM UNCERTAIN

Theory:
- Whole megakaryocytes enter systemic circulation instead of being fragmented into platelets in the lungs
- Become impacted in fingertip circulation
- Release PDGF
- Increase in fibroblasts, vascular smooth muscle cells
- → clubbing

17
Q

What is yellow nail syndrome?

A
  • Slow nail growth
  • Nails appear thickened
  • Increased longitudinal curving
    • Loss of cuticle
    • Yellow colour
18
Q

Yellow nail syndrome
Causes

A
  • Pathophysiology still unknown
  • Associated conditions:
    • Chronic lymphedema
    • Respiratory diseases
    • Chronic bronchitis
    • Bronchiectasis
    • Pleural effusions
19
Q

Apparent leukonychia
Def
Examples

A

Leuko-
- White
-nychia
- nails
‘Apparent’
- Nail plate is not truly white
- The problem is in the nail bed
- When you apply pressure to the nail, the white colour disappears

Examples:
- Muehrcke’s nails
- Half and half nails (also called Lindsay’s nails)
- Terry’s nails

20
Q

Apparent leukonychia: Muehrcke’s nails

A
  • Multiple transverse bands parallel to lunula
    Associations:
  • Hypoalbuminaemia (nephrotic syndrome, malnutrition, liver disease). Mechanism may be oedema of the nailbed.
  • Chemotherapy. Mechanism unknown.
21
Q

Apparent leukonychia: half and half nails
Def
Associations
Mechanism

A
  • Apparent leukonychia of proximal half of nail

Associations:
- Normal variant
- Chronic renal disease

Mechanism:
• Uncertain
• Nail plate may be more loosely attached to nailbed proximally

22
Q

Apparent leukonychia: Terry’s nails
Def
Associations
Mechanism

A
  • The whole nail is white, except for approx. 2mm band at the distal end.

Associations
- Normal variant
- Liver cirrhosis (but non-specific)

Mechanism
- Uncertain

23
Q

Abnormal capillaries in proximal nail fold

A
  • Seen in autoimmune connective tissue diseases:
    • Dermatomyositis and systemic sclerosis
    • These diseases damage the small capillaries of the PNF
  • May only be visible on capillaroscopy or dermoscopy.
  • Instead of regular capillary loops, see:
    • Decreased capillary density (dropout, avascular areas)
    • Giant capillaries
    • Enlarged/ dilated capillary loops

Patient with systemic sclerosis.
N – nail
G – giant capillaries
A – avascular areas
D – dilated capillary loops

24
Q

HIV and the nail

A
  • Fungal nail infections
    o Proximal subungual pattern
    o Candida onychomycosis
  • Longitudinal melanonychia (but there are many other causes of this e.g., familial, drug-induced, melanoma, other)
  • HPV-induced SCC
  • Drug-induced (Zidovudine)
25
Q

Transverse depressions (Beau’s lines)

A
  • Certain insults to the nail matrix can cause a temporary arrest in the growth of the nail plate.
  • This can cause a transverse depressions (Beau’s lines) in the nail plate, as it grows out from the matrix.
  • Examples of causes:
    • External trauma to the nail matrix e.g. manicures, nail biting
    • Childbirth
    • Systemic illness
    • Chemotherapy
26
Q

Nail shedding (Onychomadesis)

A
  • Complete cessation of nail plate growth at the nail matrix, causing shedding of the nail plate.
  • Causes are the same as for transverse depressions (Beau’s lines).
  • After coxsackie A6 virus infection in children (hand, foot and mouth disease)
27
Q

Spoon shaped nails (Koilonychia)
Causes
Pathogenesis

A

Causes
Many potential causes e.g.,
• Severe iron deficiency
• Amyloidosis
• Trauma
• Idiopathic
• Physiological in 2nd – 4th toes of young children

Pathogenesis
- Pathogenesis poorly understood.
- Proximal matrix → dorsal nail plate
- Distal matrix (lunula) → ventral nail plate
- ? Relative depression of DISTAL nail matrix due to poor blood flow

28
Q

Psoriasis and the nail

A
  • Clinical presentation depends on what part of the nail is affected by psoriatic inflammation.
  • = pitting of the proximal and distal matrix

Nail bed:
- Onycholysis (nail plate separates from nail bed)
- Subungual hyperkeratosis
- “Oil drop” sign (yellow/ orange discoloration visible through nail plate)

13. The Skin (9 decks)

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