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Dermatology Flashcards

1
Q

List the different forms of eczema

A

1) Atopic dermatitis
2) Contact dermatitis
3) Dyshidrotic dermatitis
4) Nummular dermatitis
5) Neurodermatitis
6) Sebhorreic dermatitis

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2
Q

What is the most common form of eczema?

A

Atopic dermatitis

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3
Q

What is eczema?

A

Chronic, relapsing, inflammatory skin condition characterised by an itchy red rash that favours skin creases such as folds of elbows or behind the knees (flexor surfaces)

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4
Q

How common is eczema?

A

Common

15-20% incidence during childhood

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5
Q

What are some trigger factors for atopic eczema?

A 
Exogenous:
Irritants eg soap
Skin infection eg s aureus
Contact allergens
Extremes of temp and humidity (worse at winter / sweating)
Abrasive facbrics eg wool
Dietary factors (50% children)
Inhaled allergen eg pollen

Endogenous:
Genetic mutations affecting filaggrin
Stress
Hormonal changes in women eg premenstrual flare-ups / deterioration in pregnancy

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6
Q

What is filaggrin?

A

A protein critical to the conversion of keratinocytes to the proteins/lipid squames (flake of skin) that make up the stratum corneum (outermost layer of skin)

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7
Q

What is the diagnostic criteria for atopic eczema?

A

Itchy skin plus 3 or more of:

1) Hx of itchiness on flexor surfaces
2) Hx asthma or hay fever (or hx atopic disease in a first degree relative <4yr)
3) Generally dry skin in preceding year
4) Visual flexural eczema
5) Onset in first 2 years of life

= no itching - probs not eczema

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8
Q

Where may atopic eczema present in children 18 months or under?

A

Cheeks

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9
Q

What is eczema herpeticum?

A

HSV-1 infection superimposed onto active atopic eczema

DERMATOLOGICAL EMERGENCY

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10
Q

What causes eczema herpeticum?

A

Areas of rapidly worsening, painful eczema

Clustered blistered with early-stage cold sores

Punched out erosions = circular, depressed, ulcerated lesions) usually 1-3mm that are uniform in appearance. They may coalesce to from larger areas of erosion with crusting

+/- fever, lethargy, distress, LN

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11
Q

What is the treatment of eczema herpeticum?

A

Immediate acyclovir either PO/IV

Immediate same day referral

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12
Q

What are some complications of eczema herpeticum?

A

Scarring from blisters

Infection in the cornea (herpetic keratitis) left untreated can lead to blindness

Rarely organ failure and death if virus spreads to brain, lungs and liver

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13
Q

Ddx of atopic eczema

A

1) Psoriasis - but this is extensor surfaces
2) Contact dermatitis
3) Seborrheic dermatitis
4) Fungal infections
5) Lichen simplex chronicus
6) Scabies

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14
Q

What investigations are done for atopic eczema?

A

Clinical diagnosis

IgE and specific radioallergosorbant tests (RASTs) only confirm atopic nature of individual

Swabs useful if not responding treatment identify abs-resistant s aureus or additional step infections

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15
Q

What other atopic disease are associated with atopic eczema? (3)

A

Asthma
Hay fever
Allergic rhinitis

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16
Q

What is the management of atopic eczema?

A

Avoid triggers
Emollient therapy to keep skin hydrated = at all times
Topical steroids - hydrocortisone 1% initially and increase as required
PO antihistamine may reduce itching

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17
Q

What is the ideal use of an emollient?

A

Best when skin is moist but useful at all times
Use liberally
Combo of cream, ointment, bath oil and emollient soap = max effect
- Dry areas = oil based
- Wet areas = water based

Freq of every 4 hrs or 3-4 times/day
250g/week prescription for a child

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18
Q

What is the treatment of a bacterial infection in eczema?

A

14-day course of flucloxicillin for s aureus

Erythromycin if penicillin allergy

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19
Q

What is lichenification?

A

Thick leathery patchers of skin resulting form repeated scratching

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20
Q

What is the treatment lichenification?

A

Corticosteroid

Bandages containing ichthammol paste (reduces pruritus) + zinc oxide cn be applied

Coal tar can be useful in some cases

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21
Q

What are the two types of contact dermatitis?

A

Irritant

Allergic

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22
Q

Where does dyshidrotic dermatitis affect?

A

Hands and feet

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23
Q

Who does nummular dermatitis affect?

A

M>F

Men usually first outbreak 50’s

Women get it in adolescence / early adulthood

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24
Q

How does nummular dermatitis present?

A

Coin shaped red marks

Legs, backs of hangs, forearms, lower back, hips

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25
Q

How does neurodermatitis arise?

A

Skin irritation develops in spots frequently scratched

Usually skin outbreak doesn’t get any bigger but skin can grow thick and wrinkled

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26
Q

What is sebhorreic dermatitis?

A

aka dandruff - causes skin to fall off in flakes

In infants = scalp

Adults also eyebrows / sides of nose / behind ears

Overgrowth of yeast that normally lives in these areas as well as well as overgrowth and rapid shedding of cells on scalp

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27
Q

What is the management of sebhorreic dermatitis?

A

Shampoo containing salicylic acid, selenium sulfinde, zinc pyrithione, or coal tar

Antifungal treatments can be rubbed into the areas

Steroid lotions

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29
Q

What is the prognosis of eczema?

A

Infantile eczema resolves by 2yrs in 50%

Atopic eczema resolves by age 13yr in 60%

Eczema herpeticum usually resolves in 4 weeks

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30
Q

What is impetigo?

A

Common superficial skin condition divided into non-bulbous and bulls forms

Highly infectious

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31
Q

What is the more common type of impetigo?

A

Non-bullous

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32
Q

What are the most common causative organisms of non-bullous impetigo?

A

Staph aureus
Strep pyogenes

MRSA rising

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33
Q

What are some RF for impetigo?

A

Poor hygiene
Skin conditions leading to a break in skin - atopic eczema, bites, trauma to skin, scabies, chicken pox, burns, contact dermatitis

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34
Q

How does non-bulbous impetigo present?

A

Start as tiny pustules / vesicles that evolve into honey-crusted plaques (tend to be <2cm diameter)

Usually around mouth and nose (but can be on extremities eg bites / scabies)

Satellite lesions from auto inoculation

+/- itching

Little / no surrounding erythema or oedema

Regional LN enlarged

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35
Q

How does bullous impetigo present?

A

Bullous lesions with thin roof that tend to rupture spontaneously

Usually on face, trunk, extremities, buttocks or perineal regions

More likely to occur on top of other disease eg atopic eczema

More common in neonates but can occur in any age

More likely to be painful and be associated with symptoms of malaise

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36
Q

What is ecthyma?

A

Begins as non-bullous impetigo but ulcerates and becomes necrotic

It is deeper and may occur with lymphadenitis

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37
Q

List some ddx for impetigo

A 
Contact dermatitis
Scabies
Viral skin infection eg Herpes simplex / herpes zoster
Bullous pemphigoid
Erysipelas
Atopic eczema
Burns
TJS
TEN
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38
Q

What investigations are done for impetigo?

A

Diagnosis clinical

Swab can be useful if severe / MRSA suspected / recurrent or failing to respond to treatment

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39
Q

How is impetigo managed?

A

Hygiene advice
Do not attend school until lesions are dry / scabbed over or the affected person has been on abx for 48hrs

1st line - topical fusidic acid
2nd line - topical mupirocin (if MRSA suspected)
3 times a day for 7 days

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40
Q

What may be given in severe or resistant causes of impetigo?

A

Given if <5 lesions

7 day course of flucloxacillin PO

2nd line - clarithromycin or erythromycin

NB bullous infection usually requires oral abx

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41
Q

What are some complications of impetigo?

A

If causative organism is step pyogenes, rarely can cause:
- Scarlet fevere
- Glomerulonephritis
(but most caused by staph)

Cellulitis, lymphangitis, suppurative lymphadenitis and staphylococcal scalded skin syndrome can occur

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42
Q

What is a macule?

A

Discrete flat lesion of any size or shape that are pink or red in colour

Blanching

Eg rubella or roseola

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43
Q

What is a papule?

A

Solid palpable projections above the surface of the skin

Eg insect bite

44
Q

What is is a maculopapular lesion?

A

Mixture of macule and papules which tend to be confluent

Eg measures or drug rash

45
Q

What are purpura and petechiae?

A

Purple lesions caused by small haemorrhages in the superficial layers of the skin

Generally indicate a serious condition

Non-blanching

Petechiae = tiny purpuric lesions

46
Q

What can cause purpura and petichiae?

A

Meningococcal septicaemia

Idiopathic thrombocytopenia purpura

HSP

Leukaemia

47
Q

What are vesicles?

A

Raised fluid lesions <0.5cm in diameter

Large = bull

Eg chicken pox

48
Q

What are wheals?

A

Raised lesions with a flat top and pale centre of variable size

Eg urticaria

49
Q

What is desquamation?

A

A loss of epidermal cells producing a ‘scaled’ eruption

Eg post-scarlet fever

50
Q

List 4 causes of nappy rash

Good pictures page 326 paediatrics and child health

A

1) Ammoniacal dermatitis
2) Candidiasis
3) Seborrhoeic dermatitis
4) Psoriasis

51
Q

Why is nappy rash common?

A

Area is warm and moist
Usually tightly enclosed in a waterproof covering
Contact with urine which is an irritant

52
Q

What is the most common type of nappy rash?

A

Usually simple irritant rash with candidiasis superimposed

In prolonged, resistant rash, consider seborrheic dermatitis and psoriasis

53
Q

How may a nappy rash caused by ammoniacal dermatitis present?

A

Erythematous +/- papulovesicular or bullous lesions, fissures and erosions

Patchy or confluent

Skin folds characteristically spared

From prolonged contact with urine, bacteria convert urea to ammonia which is an alkaline irritant

54
Q

How may a nappy rash caused by candida present?

A

Bright red, with sharply demarcated edge and satellite lesions

Inguinal folds involved - warm moist area promotes growth of yeast

Oral thrush may be found

55
Q

How may a nappy rash caused by seborrheic dermatitis present?

A

Pink, greasy lesions with yellow scale

Often in skin folds

Cradle cap may be found

56
Q

How may a nappy rash caused by psoriasis present?

A

Like seborrheic dermatitis

+ve FH

57
Q

What conditions may cause itching? (8)

A

1) Atopic dermatitis
2) Contact dermatitis
3) Urticaria
4) Scabies
5) Chicken pox
6) Sebhorrhoeic dermatitis
7) Head lice
8) Threadworms

58
Q

What are some common infectious skin lesions?

A

1) Warts
2) Impetigo
3) Molluscum contagiosum
4) Tinea
5) Herpes simplex
6) Brith marks

59
Q

How is a nappy rash caused by ammoniacal dermatitis managed?

A

Regular changing and washing area
Exposure to air
Protective creams eg zinc and castor oil ointment
Consider mild hydrocortisone cream
Anticandida cream can be helpful (as superimposed candida infection is v common)

60
Q

How is a nappy rash caused by candida diagnosed?

A

Usually clinically

Confirmation can be made on potassium hydroxide (KOH) preparation

61
Q

How is a nappy rash caused by candida managed?

A

Anticandidal agent eg nystatin applied at each change

If oral thrush present give PO nystatin

62
Q

How is a nappy rash caused by psoriasis managed?

A

Usually supportive and treatment kept to a minimum

Application of coal tar preparations after a bath can be helpful

Salicylic acid ointment is useful for removing scale but extensive treatment can lead to salicylate poisoning (esp young children)

Topical corticosteroids are effective but must be used with caution

63
Q

What is Stevens-Johnson syndrome (SJS)?

A

Immune-complex-mediated hypersensitivity disorder

64
Q

What are the ranges of severity of SJS?

A

Ranges from mild skin and mucous membrane lesions to a severe, sometimes fatal systemic illness - toxic epidermal necrolysis (TEN)

TEN and SJS overlap and form spectrum of severe cutaneous adverse reactions (SCAR)

Su

65
Q

What is erythema multiforme?

A

Previously considered milder form of SJS without mucosal involvement

Now distinct disorder in which there are usually only a few spots and resolve quickly

66
Q

How is SJS classified?

A

Type of lesion

Distribution of lesion

Extent of epidermal detachment:
<10% = SJS
10-30% = SJS-TEN overlap
>30% = TEN

67
Q

In which populations is SJS more common?

A

HIV
Females
Ages 10-30

Associations with HLA

68
Q

What causes SJS?

A 
75% = medications
25% = others
69
Q

What drugs are most commonly associated with SJS?

A

Allopurinol

Carbamazepine

Sulfonamides:

  • Trimethoprim-sulfamethoxazole
  • Sulfadiazina
  • Sulfasalazine

Antiviral agents:

  • Nevirapine
  • Abacavir

Anticonvulsants:

  • Phenobarbital
  • Phenytoin
  • Valproic acid
  • Lamotrigine

Others:

  • Imidazole anti fungal agents
  • NSAIDS (oxicam type eg meloxicam)
  • Salicylates
  • Sertraline
  • Bupropion (rarely)
70
Q

Other than drugs, what can cause SJS?

A

Infections

Immunisations eg measles, hep B

71
Q

What viral infections may cause SJS?

A 
HSV
SBV
Enteroviruses
HIV
Coxsackievirus
Influenza
Hepatitis
Mumps
Lymphogranuloma centrum
Rickettsia
Variola
72
Q

What bacterial infections may cause SJS?

A 
Strep pyogenes (Group A beta-haemolytic strep)
Diphtheria
Brucellosis
Mycobacteria
Mycoplasma pneumoniae
Tularaemia
Typhoid
73
Q

What fungal infections may cause SJS?

A

Coccidioidymycosis
Dermatiphytosis
Histoplasmosis

74
Q

What protozoal infections may cause SJS?

A

Malaria

Trichomoniasis

75
Q

How does SJS initially present?

A

Nonspecific URTI associated with fever, sore throat, chills, headache, arthralgia, d&v, malaise

76
Q

What may follow initial presentation of SJS?

A

Mucocutaneous lesions suddenly develop and clusters of outbreaks last 2-4 weeks

Lesions not usually pruritic

Mouth - severe oromucosal ulceration

Respiratory involvement may cause a productive cough with thick purulent sputum

Pt with genitourinary involvement may complain of dysuria or inability to pass urine

Ocular symptoms - painful red eye, purulent conjunctivitis, photophobia, blepharitis

77
Q

What general signs are associated with SJS?

A

General examination:

  • Fever
  • Tachycardia
  • Hypotension
  • Altered LOC
  • Seizures
  • Coma
78
Q

Which regions of the skin are most commonly affected in SJS?

A

Lesions can affect anywhere but most commonly affect palms, soles, dorm of hands and extensor surfaces

If confined to one area of body = usually trunk

79
Q

Describe the skin lesions associated with SJS

A

Rash begins as macule that develop into papules, vesicles, bull, urticarial plaques or confluent erythema

Centre of lesions may be vesicular, purpuric or necrotic

TARGET LESIONS = pathognomonic

Lesions may become bullous and later rupture - susceptible to 2ndary infection

Urticarial lesions are usually not pruritic

80
Q

What is nikolsky sign and what is it in SJS?

A

Mechanical pressure to skin leading to blistering within minutes or hours

Nikolsky sign positive in SJS

81
Q

Describe mucosal involvement in SJS

A 
Erythema
Oedema
Sloughing
Blistering
Ulceration
Necrolysis
82
Q

Describe eye involvement in SJS

A

Conjunctivitis

Corneal ulcerations

83
Q

Describe genital involvement in SJS

A

Erosive vulvovaginitis or balanitis

84
Q

What investigations are performed for SJS?

A

Serum electrolytes, glucose and bicarb to assess severity and level of dehydration

Diagnosis based on clinical classification and histopathology

Skin biopsy - show bullae are subepidermal
- Epidermal cell necrolysis may be seen and perivascular areas are infiltrated with lymphocytes

85
Q

What is the management of SJS?

A

MDT as many systems affected

Identify and remove cause eg drug

Use of ALDEN = Algorithim for assessment of Drug-induced Epidermal Necrolysis

Rapid assessment of prognosis using SCORTEN

Supportive

  • Airway
  • Haemodynamic stability
  • IV fluids
  • Pain control
  • Mouthwashes, topical anaesethics
  • Eye drops inc abx / steroid PRN

Treat infections

86
Q

What is SCORTEN?

A

Score for Toxic Epidermal Necrolysis = used to predict mortality rate in SJS and TEN

87
Q

What are the seven criteria of SCORTEN?

A

1) Age >40yrs
2) Presence of malignancy
3) HR >120bpm
4) Initial % of epidermal detachment >10%
5) Serum bicarb <20mmol/L
6) Serum urea >10mmol/L
7) Serum glucose >14mmol/L

Score >3 = ICU

88
Q

What are some complications of SJS?

A 
Dehydration 
Shock
VTE and DIC
GI ulceration, necrolysis, stricture and perforation
Secondary skin infection and scarring
Respiratory failure from mucosal shedding in tracheobronchial tree
Corneal ulceration and anterior uveitis 
Vaginal stenosis and penile scarring
89
Q

What is erythema nodosum?

A

Thought to be a hypersensitivity reaction

Dermatological manifestation of disease

90
Q

Is erythema nodosum more common in M or F?

A

Females

91
Q

How may erythema nodosum present?

A

Fever, aching, arthralgia

Painful rash appears within a couple of days

92
Q

Describe the course of skin lesions in erythema nodosum

A

Usually on shins

Begin as red, tender nodules with poorly defined boarders

1st week: become tense hard and painful
2nd week: fluctuant, similar to abscess but do not suppurate or ulcerate

Last for 2 weeks

93
Q

What is erythema nodosum usually indicative of?

A

Usually infectious disease but cause is not always found

Some underlying causes are not infectious

94
Q

What is the most common underlying cause of erythema nodosum?

A

Streptococcal infection

May be a feature of other diseases eg scarlet fever and rheumatic fever

95
Q

What are other underlying causes associated with erythema nodosum?

A

1) Sarcoidosis
2) TB
3) Leprosy = clinical picture of erythema nodosum but histologically different
4) Gastroenteritis causes
5) Lymphogranuloma venerum
6) Mycoplasma pneumonia
7) Fungal infections eg coccidioidomycosis
8) Drugs eg sulfonamides, sulfonylureas, gold and oral contraceptives
9) IBD - coincide with flare up
10) Precede diagnosis of Hodgkin’s and non-Hodgkin’s lymphoma by months, and can accompany Beçhet’s syndrome
11) Idiopathic

96
Q

What causes of gastroenteritis are associated with erythema nodosum?

A

Yersinia enterocolitica
Salmonella spp
Campylobacter spp

97
Q

What investigations are done for erythema nodosum?

A

Exclude serious underlying cause

  • Throat swab for strep
  • Anti-strep O (ASO) titre
  • FBC and ESR
  • Stool sample
  • Sarcoidosis = calcium and ACE raised
  • CXR may show bilateral hilarity lymphadenopathy = sarcoidosis
  • Intradermal skin tests to exclude TB or coccidioidomycosis
98
Q

How is erythema nodosum managed?

A

Most cases are self-limiting and need only symptomatic relief

Treat infective cause

RICE

NSAIDs

99
Q

What is scabies?

A

Scabies infection is caused by mite which is transmitted by direct contact

100
Q

How may scabies present?

A

Intensely purpuric eruption
Worse at night
Consisting of wheals, papules, vesicles and a superimposed eczematous dermatitis

Pathognomonic lesion = mite burrow appears as a thread-like line often in interdigital spaces, but often obliterated by scratching

In older children, head, neck, palms and soles are usually spared but often affected in babies

101
Q

How is scabies diagnosed?

A

Microscopic examination of mites obtained from scrapings

102
Q

How is scabies managed?

A

Application of scabicides - malathion or permethrin

Use with extreme caution in babies due to their toxic effects

Treat all of household and bedding and clothes washed in hot water

103
Q

Why may eczematous reaction and pruritus persist for some time following treatment of scabies?

A

Due to ongoing hypersensitivity to dead mites

104
Q

What is stasis dermatitis?

A

Results from inadequate venous return from lower limb

Over time can cause skin to develop brown stains

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