Dermatology Flashcards
(59 cards)
1
Q
What is the largest organ in the body?
A
Skin
10% of body mass of average person
2
Q
Hair Cycle:
What is the anagen stage?
A
Active growing phase
80-90% of hair
3
Q
Hair Cycle:
What is the Catagen stage?
A
2-3 week phase growth stops/follicle shrinks
1-3% of hair
4
Q
Hair cycle:
What is the Telogen stage?
A
Resting phase for 1-4 months
up to 10% of hairs in a normal scalp
5
Q
What are the functions of the Skin?
A
- Thermoregulation - insulation, heat transfer
- Skin immune system - innate and adaptive functions
- Barrier - protects against mechanical, chemical, microorganism, UV light and keeps in water and electrolytes, macromolecules.
- Sensation - temp, touch and pain
- Vitamin D synthesis - UV light converts 7-dehydrocholesterol to cholecalciferol
- Interpersonal Communication - physical appearance, smell, self-identity
6
Q
What is skin disease important? (5Ds)
A
Disfigurement Discomfort Disability Depression Death
7
Q
What are the 2 different causes of skin disease?
A
- External - temp, UV, chemical (allergen or irritant), infection, trauma
- Internal - systemic disease, genetics, drugs, infection
8
Q
What are the external causes?
A
- Photosensitivity - medications.
Exposed sites affected
- can be sensitive to UVA, UVB, visible light or a combination. - Cold injury - frostbite, chilblains, skin necrosis, cold urticaria.
- Trauma - dermatitis artefacta
- Genetic
9
Q
What are the internal causes?
A
- Drug reaction - vary in severity - good history needed. (OTC drugs)
- Autoimmune - bullous pemphigoid
10
Q
How we describe skin lesions: 1. What is a small circumscribed area?
- Larger circumscribed area?
- Small raised area?
- Larger raised area?
A
- Macule
- Patch
- Papule
- Plaque
11
Q
Describing skin lesions:
- What is small fluid filled?
- Large fluid filled
- Small pus filled
- Larger pus filled
- Loss of epidermis
- Loss of epidermis and dermis
A
- Vesicle
- Bulla
- Pustule
- Abscess
- Erosion
- Ulcer
12
Q
When would someone present with eruptive xanthoma?
A
When hyperlipidaemia is present
13
Q
When would someone present with Acanthuses nigricans?
A
Insulin resistance
Obesity
Malignancy
(Hyperkeratosis and hyper pigmentation papules - velvety appearance)
14
Q
What is thyroid skin disease?
A
Pretibial myxoedema
5% of graves disease
Skin chunks filled with mucinosis
15
Q
What investigations are carried out if bacterial infection is suspected?
A
Charcoal swab
MC&S - microscopy, culture and sensitivities
16
Q
What investigations are carried out if viral infection is suspected?
A
Viral swab for PCR
Can swab vesicle/bulla if vesicular eruption
If systemic illness, can take throat swab
17
Q
What investigations are carried out if fungal infection is suspected?
A
Skin scraping Nail clipping Hair sample Fungal cultures (skin biopsy used for all)
18
Q
What happens when the technical barrier to infection fails in the skin?
A
Sepsis
19
Q
What happens when there is failure in temperature regulation of the skin?
A
Hypo and hyper thermia
20
Q
What happens when the fluid and electrolyte balance of the skin fails?
A
Protein and fluid loss
Renal impairment
Peripheral vasodilation
21
Q
- What is Erythroderma?
2. What causes it?
A
- Any inflammatory skin disease affecting over 90% of total skin surface
- Psoriasis, Eczema, Drugs, cutaneous lymphoma, hereditary disorders, sometimes unknown
22
Q
What drug is known to cause “red man syndrome”
A
Vancomycin
23
Q
What is the management plan for Erythroderma?
A
- Appropriate setting - ITU or burns.
- Remove any offending drugs
- Careful fluid balance
- Good nutrition
- Temp regulation
- Emollients 50:50 liquid paraffin: White soft paraffin
- Oral and eye care
- Anticipate and treat infection
- Manage itch
- Treat underlying cause
24
Q
How common are drug reactions?
A
Common - 5% inpatients
- can occur to any drug
- commonly 1-2 weeks after drug (72 hours if re-challeged)
25
1. What are mild drug reactions?
| 2. What are severe drug reactions?
1. Mild - Morbilliform exanthem
| 2. Severe - Erythroderma, Stevens Johnson Syndrome/ Toxic epidermal necrolysis, DRESS
26
What is Stevens Johnson syndrome <10% / Toxic epidermal necrolysis 30% of surface epidermal detachment?
2 conditions thought to be on same spectrum - RARE.
| Secondary to drugs: antibiotics, anticonvulsants, allopurinol, NSAIDs
27
SJS clinical features
- Fever, malaise, arthralgia,
- Rash - maculopapular, target lesions, blisters, erosions covering <10% of skin surface
- Mouth ulceration
- Ulceration of other mucous membranes
28
Toxic Epidermal Necrolysis clinical features
- Often presents with prodromal febrile lines
- Ulceration of mucous membranes
Rash - macular, purpuric or blistering.
29
What is the prognosis for 1. SJS and 2. TEN?
1. Mortality up to 10%
2. Mortality up to 30%
- SCORTEN used for mortality risk.
30
Long term complications of TENS and SJS
```
Pigmentary skin changes
Scarring
Eye disease and blindness
Nail and hair loss
Joint conjectures
```
31
What is Erythema Multiform?
Hypersensitivity reaction usually triggered by infection (most commonly HSV)
- abrupt onset of up to 100s of lesions over 24hr (distal to proximal)
- Target looking lesions
- self limiting and resolves over 2 weeks.
32
What is DRESS?
Drug reaction with Eosinophilia and Systemic Symptoms:
| Onset 2-8 weeks after drug exposure, fever and widespread rash, eosinophilia and deranged liver function.
33
Management for DRESS
Stop causative drug
Symptomatic and supportive
Systemic steroids
(plus and minus immunosuppression or immunoglobulins)
34
Clinical features of Pemphigus
```
Antibodies targeted at desmosomes
Skin - flaccid blisters, rupture very easily
Intact blisters may not be seen
Common sites - face, axillae, groins
ill defined erosions in mouth
Can affect eyes, nose and genital areas.
```
35
Differences between Pemphigus and Pemphigoid
Pemphigus:
Uncommon, middle aged, blisters very fragile, mucous membranes usually affected, patients may be very unwell, TREAT with systemic steroids, dress erosions, supportive therapies.
Pemphigoid:
Common, elderly patients, blisters often intact and tense, patients fairly well, topical steroids may be sufficient if localised - systemic usually required if diffuse.
36
What is Eczema Herpeticum?
Disseminated herpes virus infection on a background of poorly controlled eczema.
37
Presentation and management for Eczema Herpeticum
Monomorphic blisters and "punched out" erosions - generally painful, not itchy., fever, lethargy.
Treatment: Aciclovir (IV or orally) Mild topical steroid if required. Treat secondary infection.
38
What is Staphylococcal Scalded skin syndrome?
| Presentation and treatment.
Initial Staph. infection.
(Common in children, or immunocompromised adults)
Erythematous rash with skin tenderness, blistering and desquamation, fever, irritability.
Admission fo IV antibiotics initially and supportive care.
39
What is Urticaria?
Weal, wheal or Hive - central swelling of variable size, surrounded by erythema. Dermal oedema.
Itching, burning, fleeting nature. (1-24hr)
Angiodema - deeper swelling of skin or mucous membranes.
40
Treatment for acute Urticaria
Oral antihistamine - 4 x dose
Short course of oral steroid
Avoid opiates and NSAIDs.
41
How does cutaneous lupus present?
Butterfly rash
Plaques with clear margins
Photosensitivity
Negative antibodies
42
What is Alopecia?
| How is it treated?
```
1. Alopecia areata - autoimmune.
T-lympocyte, cytokine rejection of hair.
- totalis
- universalis
Differential dx
Scarring alopecia
Androgenic alopecia
2. topical corticosteroids and patient care with wigs etc.
```
43
How is Lupus treated?
Hydroxychloroquine
non-steroidal anti-inflammatory drug
Corticosteroids
Lifestyle changes
44
What is vitiligo?
| How is it treated?
```
Segmental
Generalised
Destruction of melanocytes
Associated with other autoimmune conditions
2. topical steroids, phototherapy
```
45
What is acanthosis nigricans?
Can precede malignancy (GI adenocarcinoma) products, concern if:
older patient, rapid onset, involves lips and weight loss. (elephants trunk)
46
What is Dermatomyositis?
Inflammatory myopathy and rash
- Periorbital heliotrope rash
- Gottrons papules: red maculo-papular lesions over bony prominences
- Shawl sign
- photosensitive
- associated with ovarian, breast and lung cancer
47
What is normal body temp and how is it maintained?
Core temp = 37
| Maintained by balancing heat loss and heat gain
48
What 4 things are involved in thermal balance?
```
Convection = fluid conduction both ways
Conduction = heat transfer direct from objects both ways
Radiation = both ways heat loss and gain
Evaporation = sweating loss only
```
49
Where are peripheral thermoreceptors?
| Where are central thermoreceptors?
1. Located in skin
| 2. Located in spinal cord, abdominal organs and hypothalamus
50
How does the body respond to cold street?
Heat generated in body is increased by:
General metabolism
Voluntary muscular activity
Shivering thermogenesis.
51
How is heat loss from body reduced?
Vasomotor control-
sympathetic arteriolar constriction reduces delivery of blood to the skin
Behavioural responses -
reducing surface area, adding clothing, moving to warmer environment
52
What is hypothermia?
| Who is at risk?
A fall in deep body temperature to below 35.
| Neonates, elderly, cold store workers, outdoor pursuits,vagrants, north sea workers
53
What is the treatment for hypothermia?
Dry/insulate to prevent further heat loss
Slow re-warming with bag/blankets
Internal re-warming with hot drinks and warm air
Fast re-warming by immersion in water.
54
What responses do our bodies take to cold stress?
Frost bite
Vascular - vasoconstriction - promotes thrombosis - increased blood viscosity
Cellular - ice crystals form in extracellular space - cell dehydration and death
55
Heat production is minimised by what?
Decreased physical activity
| Decreased food intake
56
What increases heat loss from the body?
Vasomotor control - arterial dilation
Sweating - increases evaporation
Behavioural responses - Remove clothing
57
How does our body respond to heat stress?
Heat exhaustion
- body temp raised, vasodilation, symptoms including headache, confusion, nausea.
Heat stroke - Raised above 40, control mechanisms fail. = collapse.
58
How do you treat Heat stress?
```
Move to cool environment
Remove clothing
Fan
Sponge with tepid water
Give fluids
```
59
What is a fever?
Part of the body's mechanism for fighting infection
Caused by endogenous pyrogens
Concept of set point controlled by hypothalamus
Analogy of a thermostat that has been reset
Body temp regulates around a higher than normal body temp
Mild fever = beneficial
Severe = dangerous
