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
2
Q
What is the most common form of eczema?
A
Atopic dermatitis
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)
4
Q
How common is eczema?
A
Common
15-20% incidence during childhood
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
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)
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
8
Q
Where may atopic eczema present in children 18 months or under?
A
Cheeks
9
Q
What is eczema herpeticum?
A
HSV-1 infection superimposed onto active atopic eczema
DERMATOLOGICAL EMERGENCY
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
11
Q
What is the treatment of eczema herpeticum?
A
Immediate acyclovir either PO/IV
Immediate same day referral
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
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
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
15
Q
What other atopic disease are associated with atopic eczema? (3)
A
Asthma
Hay fever
Allergic rhinitis
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
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
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
19
Q
What is lichenification?
A
Thick leathery patchers of skin resulting form repeated scratching
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
21
Q
What are the two types of contact dermatitis?
A
Irritant
Allergic
22
Q
Where does dyshidrotic dermatitis affect?
A
Hands and feet
23
Q
Who does nummular dermatitis affect?
A
M>F
Men usually first outbreak 50’s
Women get it in adolescence / early adulthood
24
Q
How does nummular dermatitis present?
A
Coin shaped red marks
Legs, backs of hangs, forearms, lower back, hips
25
How does neurodermatitis arise?
Skin irritation develops in spots frequently scratched
Usually skin outbreak doesn't get any bigger but skin can grow thick and wrinkled
26
What is sebhorreic dermatitis?
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
27
What is the management of sebhorreic dermatitis?
Shampoo containing salicylic acid, selenium sulfinde, zinc pyrithione, or coal tar
Antifungal treatments can be rubbed into the areas
Steroid lotions
29
What is the prognosis of eczema?
Infantile eczema resolves by 2yrs in 50%
Atopic eczema resolves by age 13yr in 60%
Eczema herpeticum usually resolves in 4 weeks
30
What is impetigo?
Common superficial skin condition divided into non-bulbous and bulls forms
Highly infectious
31
What is the more common type of impetigo?
Non-bullous
32
What are the most common causative organisms of non-bullous impetigo?
Staph aureus
Strep pyogenes
MRSA rising
33
What are some RF for impetigo?
Poor hygiene
Skin conditions leading to a break in skin - atopic eczema, bites, trauma to skin, scabies, chicken pox, burns, contact dermatitis
34
How does non-bulbous impetigo present?
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
35
How does bullous impetigo present?
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
36
What is ecthyma?
Begins as non-bullous impetigo but ulcerates and becomes necrotic
It is deeper and may occur with lymphadenitis
37
List some ddx for impetigo
```
Contact dermatitis
Scabies
Viral skin infection eg Herpes simplex / herpes zoster
Bullous pemphigoid
Erysipelas
Atopic eczema
Burns
TJS
TEN
```
38
What investigations are done for impetigo?
Diagnosis clinical
Swab can be useful if severe / MRSA suspected / recurrent or failing to respond to treatment
39
How is impetigo managed?
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
40
What may be given in severe or resistant causes of impetigo?
Given if <5 lesions
7 day course of flucloxacillin PO
2nd line - clarithromycin or erythromycin
NB bullous infection usually requires oral abx
41
What are some complications of impetigo?
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
42
What is a macule?
Discrete flat lesion of any size or shape that are pink or red in colour
Blanching
Eg rubella or roseola
43
What is a papule?
Solid palpable projections above the surface of the skin
Eg insect bite
44
What is is a maculopapular lesion?
Mixture of macule and papules which tend to be confluent
Eg measures or drug rash
45
What are purpura and petechiae?
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
What can cause purpura and petichiae?
Meningococcal septicaemia
Idiopathic thrombocytopenia purpura
HSP
Leukaemia
47
What are vesicles?
Raised fluid lesions <0.5cm in diameter
Large = bull
Eg chicken pox
48
What are wheals?
Raised lesions with a flat top and pale centre of variable size
Eg urticaria
49
What is desquamation?
A loss of epidermal cells producing a 'scaled' eruption
Eg post-scarlet fever
50
List 4 causes of nappy rash
| Good pictures page 326 paediatrics and child health
1) Ammoniacal dermatitis
2) Candidiasis
3) Seborrhoeic dermatitis
4) Psoriasis
51
Why is nappy rash common?
Area is warm and moist
Usually tightly enclosed in a waterproof covering
Contact with urine which is an irritant
52
What is the most common type of nappy rash?
Usually simple irritant rash with candidiasis superimposed
In prolonged, resistant rash, consider seborrheic dermatitis and psoriasis
53
How may a nappy rash caused by ammoniacal dermatitis present?
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
How may a nappy rash caused by candida present?
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
How may a nappy rash caused by seborrheic dermatitis present?
Pink, greasy lesions with yellow scale
Often in skin folds
Cradle cap may be found
56
How may a nappy rash caused by psoriasis present?
Like seborrheic dermatitis
+ve FH
57
What conditions may cause itching? (8)
1) Atopic dermatitis
2) Contact dermatitis
3) Urticaria
4) Scabies
5) Chicken pox
6) Sebhorrhoeic dermatitis
7) Head lice
8) Threadworms
58
What are some common infectious skin lesions?
1) Warts
2) Impetigo
3) Molluscum contagiosum
4) Tinea
5) Herpes simplex
6) Brith marks
59
How is a nappy rash caused by ammoniacal dermatitis managed?
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
How is a nappy rash caused by candida diagnosed?
Usually clinically
Confirmation can be made on potassium hydroxide (KOH) preparation
61
How is a nappy rash caused by candida managed?
Anticandidal agent eg nystatin applied at each change
If oral thrush present give PO nystatin
62
How is a nappy rash caused by psoriasis managed?
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
What is Stevens-Johnson syndrome (SJS)?
Immune-complex-mediated hypersensitivity disorder
64
What are the ranges of severity of SJS?
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
What is erythema multiforme?
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
How is SJS classified?
Type of lesion
Distribution of lesion
Extent of epidermal detachment:
<10% = SJS
10-30% = SJS-TEN overlap
>30% = TEN
67
In which populations is SJS more common?
HIV
Females
Ages 10-30
Associations with HLA
68
What causes SJS?
```
75% = medications
25% = others
```
69
What drugs are most commonly associated with SJS?
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
Other than drugs, what can cause SJS?
Infections
| Immunisations eg measles, hep B
71
What viral infections may cause SJS?
```
HSV
SBV
Enteroviruses
HIV
Coxsackievirus
Influenza
Hepatitis
Mumps
Lymphogranuloma centrum
Rickettsia
Variola
```
72
What bacterial infections may cause SJS?
```
Strep pyogenes (Group A beta-haemolytic strep)
Diphtheria
Brucellosis
Mycobacteria
Mycoplasma pneumoniae
Tularaemia
Typhoid
```
73
What fungal infections may cause SJS?
Coccidioidymycosis
Dermatiphytosis
Histoplasmosis
74
What protozoal infections may cause SJS?
Malaria
| Trichomoniasis
75
How does SJS initially present?
Nonspecific URTI associated with fever, sore throat, chills, headache, arthralgia, d&v, malaise
76
What may follow initial presentation of SJS?
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
What general signs are associated with SJS?
General examination:
- Fever
- Tachycardia
- Hypotension
- Altered LOC
- Seizures
- Coma
78
Which regions of the skin are most commonly affected in SJS?
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
Describe the skin lesions associated with SJS
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
What is nikolsky sign and what is it in SJS?
Mechanical pressure to skin leading to blistering within minutes or hours
Nikolsky sign positive in SJS
81
Describe mucosal involvement in SJS
```
Erythema
Oedema
Sloughing
Blistering
Ulceration
Necrolysis
```
82
Describe eye involvement in SJS
Conjunctivitis
| Corneal ulcerations
83
Describe genital involvement in SJS
Erosive vulvovaginitis or balanitis
84
What investigations are performed for SJS?
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
What is the management of SJS?
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
What is SCORTEN?
Score for Toxic Epidermal Necrolysis = used to predict mortality rate in SJS and TEN
87
What are the seven criteria of SCORTEN?
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
What are some complications of SJS?
```
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
What is erythema nodosum?
Thought to be a hypersensitivity reaction
Dermatological manifestation of disease
90
Is erythema nodosum more common in M or F?
Females
91
How may erythema nodosum present?
Fever, aching, arthralgia
| Painful rash appears within a couple of days
92
Describe the course of skin lesions in erythema nodosum
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
What is erythema nodosum usually indicative of?
Usually infectious disease but cause is not always found
Some underlying causes are not infectious
94
What is the most common underlying cause of erythema nodosum?
Streptococcal infection
May be a feature of other diseases eg scarlet fever and rheumatic fever
95
What are other underlying causes associated with erythema nodosum?
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
What causes of gastroenteritis are associated with erythema nodosum?
Yersinia enterocolitica
Salmonella spp
Campylobacter spp
97
What investigations are done for erythema nodosum?
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
How is erythema nodosum managed?
Most cases are self-limiting and need only symptomatic relief
Treat infective cause
RICE
NSAIDs
99
What is scabies?
Scabies infection is caused by mite which is transmitted by direct contact
100
How may scabies present?
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
How is scabies diagnosed?
Microscopic examination of mites obtained from scrapings
102
How is scabies managed?
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
Why may eczematous reaction and pruritus persist for some time following treatment of scabies?
Due to ongoing hypersensitivity to dead mites
104
What is stasis dermatitis?
Results from inadequate venous return from lower limb
Over time can cause skin to develop brown stains
