Dermatology Flashcards
What is the largest organ in the body?
Skin
10% of body mass of average person
Hair Cycle:
What is the anagen stage?
Active growing phase
80-90% of hair
Hair Cycle:
What is the Catagen stage?
2-3 week phase growth stops/follicle shrinks
1-3% of hair
Hair cycle:
What is the Telogen stage?
Resting phase for 1-4 months
up to 10% of hairs in a normal scalp
What are the functions of the Skin?
- 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
What is skin disease important? (5Ds)
Disfigurement Discomfort Disability Depression Death
What are the 2 different causes of skin disease?
- External - temp, UV, chemical (allergen or irritant), infection, trauma
- Internal - systemic disease, genetics, drugs, infection
What are the external causes?
- 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
What are the internal causes?
- Drug reaction - vary in severity - good history needed. (OTC drugs)
- Autoimmune - bullous pemphigoid
How we describe skin lesions: 1. What is a small circumscribed area?
- Larger circumscribed area?
- Small raised area?
- Larger raised area?
- Macule
- Patch
- Papule
- Plaque
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
- Vesicle
- Bulla
- Pustule
- Abscess
- Erosion
- Ulcer
When would someone present with eruptive xanthoma?
When hyperlipidaemia is present
When would someone present with Acanthuses nigricans?
Insulin resistance
Obesity
Malignancy
(Hyperkeratosis and hyper pigmentation papules - velvety appearance)
What is thyroid skin disease?
Pretibial myxoedema
5% of graves disease
Skin chunks filled with mucinosis
What investigations are carried out if bacterial infection is suspected?
Charcoal swab
MC&S - microscopy, culture and sensitivities
What investigations are carried out if viral infection is suspected?
Viral swab for PCR
Can swab vesicle/bulla if vesicular eruption
If systemic illness, can take throat swab
What investigations are carried out if fungal infection is suspected?
Skin scraping Nail clipping Hair sample Fungal cultures (skin biopsy used for all)
What happens when the technical barrier to infection fails in the skin?
Sepsis
What happens when there is failure in temperature regulation of the skin?
Hypo and hyper thermia
What happens when the fluid and electrolyte balance of the skin fails?
Protein and fluid loss
Renal impairment
Peripheral vasodilation
- What is Erythroderma?
2. What causes it?
- Any inflammatory skin disease affecting over 90% of total skin surface
- Psoriasis, Eczema, Drugs, cutaneous lymphoma, hereditary disorders, sometimes unknown
What drug is known to cause “red man syndrome”
Vancomycin
What is the management plan for Erythroderma?
- 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