(PM3A - Scabies, Lice, Boils, Impetigo, Wound Healing Flashcards

1
Q

What is scabies?

A

Infestation of the skin with a mite

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2
Q

What causes scabies?

A

Sarcoptes scabiei

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3
Q

Where do scabies live

A

In burrowed tunnels in the stratum corneum

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4
Q

How long are the burrows of scabies?

A

A few mm-1cm long

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5
Q

Where are scabies most often found on the body?

A

Between the fingers + on the wrists

Waistline + genitals

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6
Q

How are scabies transmitted?

A

Direct contact

Animal transmission can occur

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7
Q

What is the primary risk factor for scabies?

A

Crowded conditions

e.g. schools/ homeless shelters

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8
Q

How do scabies infections present?

A

Pruritic lesions - worse at night

Erythematous papules

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9
Q

What types of scabies are there?

A

(1) Classic scabies

(2) Crusted (Norwegian) scabies

(3) Nodular scabies

(4) Bullous scabies

(5) Scalp scabies

(6) Scabies incognito

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10
Q

How is an infection of crusted (Norwegian) scabies caused?

A

Impaired immune system in a classic scabies infection

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11
Q

What is nodular scabies?

A

More common in infants + young children

Likely due to a hypersensitivity to these organisms

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12
Q

What are bullous scabies?

A

Occurs in children + elderly

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13
Q

When do scalp scabies occur?

A

Infants + immunocompromised patients

Appear similar to seborrhoeic eczema

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14
Q

What causes scabies incognito?

A

Application of topical corticosteroids

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15
Q

What is scabies incognito?

A

Widespread atypical presentation of scabies

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16
Q

How are scabies diagnosed?

A

(1) Examination

(2) Skin scrapings

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17
Q

What is the first line treatment for scabies?

A

Scabicides

e.g. permethrin

Applied to entire body from neck down, washed off after 8-14hrs, repeat after 7 days

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18
Q

What is permethrin used to treat?

A

Scabies infections

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19
Q

How does application of permethrin differ in infants and young children?

A

Should be applied ALSO to head + neck

AVOID periorbital + perioral regions

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20
Q

When is lindane contraindicated for scabies infections?

A

(1) <2yrs old

(2) Seizure disorder

Potential neurotoxicity

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21
Q

What is the treatment for crusted (Norwegian) scabies?

A

Ivermectin

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22
Q

When is ivermectin indicated ahead of permethrin for scabies?

A

Crusted (Norwegian) scabies

Patients who do not respond to topical treatment

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23
Q

Who/ what should be treated in a scabies infection?

A

(1) Patient

(2) Close contacts

(3) Personal items - store for 3 days/ washed

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24
Q

What is the treatment for pruritus?

A

Corticosteroid ointments

Oral antihistamines

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25
Q

Define pruritus?

A

Severe itching of the skin

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26
Q

How long can symptoms and lesions (pruritus) be expected to take to heal following treatment?

A

Up to 3 weeks

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27
Q

What are lice?

A

Wingless blood-sucking insects

2-5mm in length

Infest scalp, pubis, body, or eyelashes

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28
Q

Where can lice infections occur?

A

(1) Scalp

(2) Eyelashes

(3) Body

(4) Pubis

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29
Q

How long can lice live without a human host?

A

Up to 30 days

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30
Q

How are head lice transmitted?

A

Close contact

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31
Q

How are body lice transmitted?

A

Cramped + close conditions

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32
Q

How are pubic lice transmitted?

A

Sexual contact

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33
Q

What are pubic lice called?

A

Crabs

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34
Q

What is the correct term for crabs?

A

Pubic lice

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35
Q

How can lice cause contraction of other diseases?

A

Lice can act as vectors

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36
Q

At what age is head lice most common?

A

Girls aged 5-11yrs

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37
Q

In what patient group are head lice most uncommon?

A

Afro-Caribbeans

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38
Q

How many lice are commonly present to cause an active infestation?

A

<20 lice

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39
Q

What is the main symptom of head lice infestations?

A

Severe pruritus - skin itching

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40
Q

How is a head lice infestation diagnosed?

A

Combing through wet hair with fine-toothed lice comb

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41
Q

Where on the scalp are head lice most often found?

A

Back of head

Behind ears

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42
Q

What are nits?

A

Greyish-white eggs

Fixed to the base of hair shafts

Baby head lice

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43
Q

What are higher in number on the scalp during a lice infestation, nits or lice?

A

Nits

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44
Q

Where do body lice primarily live?

A

Bedding/ clothing

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45
Q

Where are body lice most commonly found?

A

Crowded conditions

e.g. barracks/ low socio-economic status

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46
Q

How are body lice transmitted?

A

Sharing contaminated clothing/ bedding

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47
Q

What is the most significant symptom of body lice?

A

Intense pruritus - skin itching

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48
Q

What can be observed in a body lice infestation?

A

Small red puncta caused by bites

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49
Q

How is a body lice infestation diagnosed?

A

Demonstration of nits/ lice in clothing

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50
Q

What is the treatment for head lice?

A

(1) Treatment of all family members

(2) Mechanical removal (avoids irritants)

(3) Comb every 4 days for 2 weeks - due to hatching of nits

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51
Q

What medications can be used for treatment of head lice?

A

(1) Permethrin

(2) Dimeticone (4%)

(3) Malathion (0.5%)

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52
Q

How should dimeticone 4% be applied?

A

(1) Apply to dry hair + scalp

(2) Allow to dry naturally

(3) Wash off after 8hrs

(4) Repeat after 7 days

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53
Q

How should malathion 0.5% be applied?

A

(1) Apply to dry hair + scalp

(2) Allow to dry naturally

(3) Wash off after 12hrs

(4) Repeat after 7 days

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54
Q

What is the treatment for body lice?

A

Treatment of pruritus

Treatment of any secondary infection

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55
Q

Why is there no direct treatment for body lice?

A

Body lice live in clothing/ bedding, not on the body

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56
Q

What is the treatment for pubic lice (crabs)?

A

Malathion 0.5%

Apply over whole body + allow to dry naturally

Wash off after 12hrs

Repeat after 7 days

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57
Q

How is a lice infestation of the eyelashes treated?

A

Petrolatum ointment applied to eyelids

Apply TDS-QDS

Duration of 8-10 days

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58
Q

What are boils?

A

Skin abscesses

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59
Q

What other names for boils?

A

Furuncles

Carbuncles

60
Q

What causes boils?

A

Tender nodules caused by Staphylococcal infection

Often of the hair follicle

61
Q

What are furuncles?

A

Type of boil

Common on face/ neck/ breasts/ buttocks

Appear as nodules/ pustules

62
Q

What are carbuncles?

A

Type of boil

Cluster of furuncles

Connected subcutaneously

63
Q

What are the common risk factors for boils?

A

(1) Bacterial colonisation of skin

(2) Hot/ humid climates

(3) Occlusion/ abnormal follicular anatomy

64
Q

Which patient groups are more predisposed to boils?

A

(1) Obese

(2) Immunocompromised

(3) Diabetic

(4) Elderly

65
Q

How are boils diagnosed?

A

Examination

Cultures should be obtained for single furuncles on nose/ face + multiple furuncles + immunocompromised patients

66
Q

What is the treatment for a single boil lesion?

A

Intermittent hot compresses

To allow it to drain

67
Q

What is the treatment for a furuncle in the nose/ central face area?

A

Topical antibiotics

68
Q

When are systemic antibiotics required for boils?

A

(1) Larger lesions

(2) Lesions that do not respond to topical care

(3) Evidence of expanding cellulitis

(4) Immunocompromised patients

69
Q

How can recurrence of furuncles be prevented?

A

Application of liquid soap

i.e. chlorhexidine gluconate with isopropyl alcohol

70
Q

What is impetigo?

A

Superficial skin infection with crusting

Caused by Streptococci/ Staphylococci

71
Q

Which microorganism causes impetigo?

A

Staphylococci/ Streptococci

72
Q

How does an impetigo infection start?

A

Can follow any break in the skin

73
Q

What are some risk factors for impetigo?

A

(1) Moist environment

(2) Poor hygiene

(3) Chronic nasal carriage of staphylococci

74
Q

How does impetigo present?

A

(1) Clusters of vesicles/ pustules

(2) Develop a honey-coloured crust

75
Q

What is ecthyma?

A

Ulcerative form of impetigo

76
Q

How does ecthmya present?

A

Small + shallow

Punched out ulcers

Thick + brown/ black crusts

Erythema (redness)

77
Q

What is an issue with pruritus of impetigo?

A

Scratching can spread infection

78
Q

How are impetigo and ecthyma diagnosed?

A

(1) Characteristic appearance

(2) Cultures of lesions when patient not responsive to initial therapy

(3) Nasal culture for recurrent impetigo

79
Q

What is the treatment for impetigo and ecthyma?

A

Localised infection treated with fusidic acid 2%

TDS/ QDS

80
Q

How is an impetigo/ ecthyma infection caused by MRSA treated?

A

Topical mupirocin 2%

TDS for 10 days

81
Q

How is an extensive impetigo/ ecthyma infection treated?

A

Oral

Flucloxacillin/ clarithromycin

82
Q

What is photosensitivity?

A

Poorly understood

Reaction of skin to sunlight

Likely to involve immune system

83
Q

What are some symptoms of photosensitivity?

A

(1) Redness

(2) Rash

(3) Urticaria - hives

Can also lead to dizziness/ wheezing etc

84
Q

Can drugs increase risk of photosensitivity?

A

Yes

Phenothiazines

85
Q

What is the treatment for photosensitivity?

A

Depends on cause

(1) Unusual reaction w/ brief exposure = skin disorder/ systemic disease

(2) Use of chemicals + exposure = Topical corticosteroids + avoid chemical

86
Q

What is drug-induced photosensitivity?

A

Increased sensitivity to sunlight due to exposure to certain drug/ chemical

87
Q

What are the types of drug-induced photosensitivity?

A

(1) Phototoxicity

(2) Photoallergy

88
Q

What is phototoxicity?

A

Light-absorbing compounds directly generate inflammatory mediators + free radicals

Causes tissue damage + pain + erythema

Typically caused by topicals or ingested agents

ONLY present on sun-exposed skin

89
Q

What is a photoallergy?

A

Type 4 (cell-mediated) allergic response

Light absorption causes structural changes to drug/ chemical

Drug then binds to a tissue protein and acts as a hapten

Prior exposure is required

90
Q

What are some common causes of photoallergic reactions?

A

(1) Aftershave lotions

(2) Sun creams

(3) Sulfonamides

91
Q

What are the symptoms of a photoallergic reaction?

A

(1) Erythema - redness

(2) Pruritus - itching

Sometimes vesicles

92
Q

What are burns?

A

Injuries of the skin/ other tissue

Thermal/ chemical/ radiation/ electrical contact

93
Q

How are burns classified?

A

By depth + % of body surface area involved

94
Q

What type of burn is sunburn?

A

Radiation burn

95
Q

How do burns damage the skin?

A

Protein denaturation + coagulation necrosis

Can get a bacterial infection through damaged epidermis

96
Q

How do burns cause heat loss?

A

Impaired thermoregulation due to damaged dermis

97
Q

What is the risk with a higher percentage of burnt surface area of the body?

A

Increased risk of developing systemic complications

98
Q

What are the risk factors for severe complications/ death from burns?

A

(1) >40% body surface area

(2) >60yrs old

(3) <2yrs old

(4) Simultaneous major trauma/ smoke inhalation

99
Q

How is a first degree burn characterised?

A

Red + blanch markedly w/ light pressure

Painful + tender

Limited to epidermis

100
Q

How are second degree burns characterised?

A

Partial thickness

Involves part of the dermis

Sub-divided into superficial + deep

101
Q

What is a superficial 2nd degree burn?

A

Upper half of dermis

2-3 weeks heal time

Rarely scar unless infected

Intense pain + tender

Vesicle development within 24 hours

102
Q

What is a deep 2nd degree burn?

A

Bottom half of dermis

> 3 week heal time

Scarring is common

Do not blanch

LESS painful than superficial burns

Burns are very dry

103
Q

How are third degree burns classified?

A

Full thickness

Extend through entire dermis + into underlying fat

104
Q

How are burns treated?

A

Examination + treatment as soon as patient is stable

Estimate extent of burn (handprint = ~1%)

Remove clothing covering burn

Flush chemicals off (powders are brushed)

Acid/ alkali burns with water for 20 mins

> 15% surface area given IV fluids

Clean burn wound + apply topical antibacterial salve + sterile dressing

105
Q

What is an example of a topical antibacterial salve applied for burns?

A

Silver sulphadiazine

106
Q

How is the ongoing treatment of burns managed?

A

Daily changing of dressings

Complete cleaning of burn with water

Application of a new layer of antibacterial salve

Surgery/ grafting for all 3rd degree burns and those that do not heal <3 weeks

107
Q

Where is a skin graft often taken from?

A

Healthy skin, e.g. thigh

Skin graft is cut into a mesh

108
Q

What happens to skin that is taken for a graft before being transplanted?

A

Graft is cut into a mesh

To cover larger surface area

109
Q

Why are skin grafts cut into a mesh prior to retransplantation?

A

To increase surface area

Can increase 2-3x

110
Q

What is a wound?

A

A physical break in the skin

Tear/ cut/ erosion/ puncture/ ulcer
Break in the skin barrier

111
Q

What are some types of trauma wound types?

A

(1) Abrasion/ graze - superficial, epidermis scraped off

(2) Laceration - irregular tear

(3) Avulsion - removal of all skin layers by abrasion

(4) Incision - regular slice with clean sharp object

(5) Puncture - e.g. needle/ nail

(6) Amputation

112
Q

How many types of wound classification are there?

A

4 types

(1) Necrotic
(2) Sloughy
(3) Granulating
(4) Epithelialising

113
Q

What is a necrotic wound?

A

Dead/ ischaemic tissue

Usually black + covered with dead epidermis

114
Q

What is a sloughy wound?

A

Often yellow

Due to cellular debris/ fibrin/ serum exudate/ bacteria

115
Q

What is a granulating wound?

A

Typically pink/ red

Highly vascularised

Irregular + granular appearance

116
Q

What is an epithelialising wound?

A

Cells migrate from wound edges

Start the process of re-epithelialisation

See a pink wound bed

117
Q

What are the stages in wound healing?

A

(1) Haemostasis

(2) Inflammation

(3) Proliferation

(4) Maturation/ remodelling

118
Q

What is the process of haemostasis?

A

The first process in wound healing

(1) Vasoconstriction following injury
(2) Platelet aggregation
(3) Coagulation cascade
(4) Haemostatic plug/ clot seal damaged vessel

119
Q

What is inflammation?

A

Redness/ heat/ pain/ swelling

Typically 4-5 days

Initiates healing process

Stabilises wound through platelet activity

Neutrophils/ monocytes/ macrophages control bacterial growth

Red colour + warmth caused by capillary blood system increasing circulation

120
Q

What is proliferation?

A

Begins within 24hrs of initial injury

Continues for up to 21 days

Characterised by:
(1) Epithelialisation
(2) Granulation
(3) Collagen synthesis

121
Q

What is granulation?

A

Formulation of new capillaries - angiogenesis

‘Beefy’ red tissue

Bleeds easily

Fibrous connective tissue replaces fibrin clot

Grows from the base of the wound

122
Q

What is epithelialisation?

A

Formation of epithelial layer

Seals + protects wound from bacteria + fluid loss

Must have a moist environment for faster growth

Initially fragile - can be easily destroyed

123
Q

What is collagen synthesis?

A

Creation of a support matrix for new tissue

Provide structural strength

Oxygen + iron + vitamin C + magnesium + zinc + protein are VITAL for collagen synthesis

The actual rebuilding of the skin barrier

124
Q

What is wound contraction?

A

Large wounds can be 40-80% smaller after contraction

Can continue for weeks - even after wound has been completely re-epithelialised

Usually does not occur symmetrically

125
Q

What is maturation?

A

Final stage of wound healing

Begins ~21 days after injury

Can continue for ≤2 years

Begins when collagen synthesis + degradation equalise

Type 3 collagen is gradually replaced with Type 1 collagen

Collagen fibres are rearranged and cross-linked (aligned along tension lines)

126
Q

What type of collagen is produced in initial collagen synthesis? What happens to this?

A

Type 3 collagen

Gradually replaced with Type 1 collagen during maturation

127
Q

What are Langer’s lines?

A

Direction that skin will split when a human cadaver is hit with a spike

128
Q

Describe the changes to the tensile strength of the wound in maturation/ re-modelling.

A

Tensile strength increases

~50% of normal tissue’s tensile strength after 3 months

~80% of normal tissue’s tensile strength after full healing

129
Q

What are the different types of wound healing?

A

(1) Primary healing - healing by first intention

(2) Secondary healing - healing by secondary intention

(3) Delayed primary healing - healing by tertiary intention

130
Q

What is primary wound closure?

A

Wound edges re-approximated to be adjacent to each other

Most surgical wounds heal this way

Closure performed with sutures/ staples/ adhesive tape

Minimises scarring + infection risk

131
Q

What is secondary wound closure?

A

Wound is allowed to granulate

Wound may be packed with gauze

Granulation causes broader scar than first intent

Healing can slow due to drainage from infection

Daily wound care required - encourage wound debris removal to allow for granulation formation

Prevents haematoma development

132
Q

What is delayed primary healing?

A

Wound is purposely left open

Wound cleaned + debrided + observed

4th day phagocytosis of contaminated tissues

Wound closed surgically after 4-5 days

Can result in significant scarring if wound is not cleaned effectively

133
Q

What are scars?

A

Areas of fibrous tissue

  • Natural part of the healing process
  • Result from wounds
134
Q

Describe the collagen arrangement of normal skin.

A

‘Basket-weave’

135
Q

Describe the collagen arrangement of scar tissue.

A

Highly orientated

Weaker to future trauma, e.g. UV radiation

136
Q

What does not regrow in scar tissue?

A

(1) Sweat glands

(2) Hair follicles

137
Q

What happens if myofibroblasts are not cleared by apoptosis?

A

May get keloid/ hypertrophic scars

138
Q

How are myofibroblasts (from scarring) removed?

A

By apoptosis

139
Q

What is a hypertrophic scar?

A

Over-production of collagen

Scar raised above surface

Typically red

Less common following surgery

More common for wounds closed by secondary intent

140
Q

What is a keloid?

A

Overgrowth of collagen

Formation of rubbery/ shiny nodules

Pink/ red/ brown

Can grow into large benign tissue

Completely harmless + non-cancerous

Can be itchy/ painful

Most common on shoulders/ chest

141
Q

What is an atrophic scar?

A

Sunken recess in the skin

Pitted appearance

Caused when underlying skin structures are lost
- e.g. muscle/ fat

Often with acne/ chickenpox

142
Q

What are stretch marks?

A

Type of scar

AKA. striae

Common during pregnancy/ weight gain/ growth spurts

Occur when skin is put under tension during healing process

143
Q

What is the purpose of scar treatment?

A

For cosmetic purposes

144
Q

How can scars be treated?

A

(1) Chemical peels: for superficial scars

(2) Filler infections: for atrophic (sunken) scars

(3) Dermabrasion: Remove top layer of scar tissue

(4) Laser:
- Can heat + redistribute collagen in keloids (non-ablative)
- Can remove outer skin layers (ablative) not for keloids

(5) Radiotherapy: Low dose can help keloids
- Not recommended - significant adverse effects

(6) Ointments + pressure dressings
- No strong evidence of support

(7) Steroids: Inject steroid into scar
- Can thin + soften the scar

(8) Surgery: Remove scar (keloids recur 45%)

145
Q

Following surgical removal, what is the recurrence percentage of keloid scars?

A

45%