Introduction to dermatology Flashcards
What does adnexa mean?
Adnexa - the appendages of an organ
What are the 3 main layers of the skin?
Epidermis
Dermis
Hypodermis
What are the 5 layers of the epidermis?
o Stratum corneum o Stratum lucidum o Stratum granulosum o Stratum spinosum o Stratum basale
What are the 3 hair stages in the hair growth cycle?
Anagen
– Active growing phase
– 80-90% of hairs
Catagen
– 2–3 week phase growth stops/follicle shrinks
– 1–3% of hairs
Telogen
– Resting phase for 1–4 months
– Up to 10% of hairs in a normal scalp
What % of hair is in anagen?
80-90%
What % of hair is in catagen?
1-3%
What % of hair is in telogen?
10%
What are the 6 functions of the skin?
Thermoregulation - Insulation, Heat transfer
Skin immune system - Innate and Adaptive functions
Barrier - Protects against Mechanical, Chemical, microorganisms, Ultraviolet light. Keeps in water and Electrolytes, Macromolecules
Sensation - Temperature, touch and pain
Vitamin D synthesis - UV light converts 7-dehydrocholesterol to cholecalciferol
Interpersonal Communication - Physical appearance, smell, self -identity
What % of the population have skin disease?
22-30%
Why is skin disease so important?
5 Ds
- Disfigurement
- Discomfort
- Disability
- Depression
- Death
What are the two classes of causative agents for skin disease?
External
– Temperature, UV, chemical (allergen or irritant), infection, trauma
Internal
– Systemic disease, genetics, drugs, infection, AI disease
What is dermatitis artefacta?
Self inflicted skin lesions
What is a macule?
Macule - small (<5mm) circumscribed area (area of discolouration)
What is a patch?
Patch - larger (>5mm) circumscribed area (area of discolouration)
What is a papule?
Papule - small (<5mm) raised area
What is a plaque?
Plaque - larger (>5mm) raised area
What is a nodule?
A nodule is a large circumscribed swelling within the surface of the skin
What is a tumour?
The term tumour also means swelling similar to a nodule, but has acquired the specific implication of a growth of new cells, either benign or malignant
What is a vesicle?
Vesicle - small (<5mm) fluid filled lesion
What is a bulla?
Bulla - large (>5mm) fluid filled lesion
What is a pustule?
Pustule - small (<5mm) pus filled lesion
What is an abscess?
Abscess - large (>5mm) pus filled lesion
Define erosion
Loss of epidermis
Define ulcer
Loss of epidermis and dermis
Describe urticaria
Hives, also known as urticaria, is a kind of skin rash with red, raised, itchy bumps. They may also burn or sting.
Describe bullous pemphigoid
Bullous pemphigoid is an acute or chronic autoimmune skin disease, involving the formation of blisters, more appropriately known as bullae, at the space between the epidermis and dermis skin layers. It is classified as a type II hypersensitivity reaction, with the formation of anti-hemidesmosome antibodies
Describe Leukocytoclastic vasculitis
Leukocytoclastic vasculitis (LCV), also known as hypersensitivity vasculitis and hypersensitivity angiitis, is a histopathologic term commonly used to denote a small-vessel vasculitis
List some skin diseases associated with hypersensitivity reactions
Bullous pemphigoid
Leukocytoclastic vasculitis
What conditions can be aided in diagnosis by cutaneous signs?
o Erythema Nodosum o Sarcoidosis o Vasculitis o Malignancy o Auto-immune conditions
What condition can be suspected if eruptive xanthoma is seen on the skin?
Hyperlipidaemia
What conditions can be linked to Acanthosis Nigricans?
Insulin resistance
Obesity
Malignancy
Describe pretibial myxoedema and what diseases it might be seen in
Pretibial myxedema is an infiltrative dermopathy, resulting as a rare complication of Graves’ disease
What investigations would be carried out if a bacterial infection of the skin is suspected?
Charcoal swab
Ask for MC&S
• Microscopy
• Culture
• Sensitivities
What investigations would be carried out if a viral infection of the skin is suspected?
o Viral swab for PCR
o Can swab vesicle/bulla if vesicular eruption
o If systemic illness, can take throat swab
What investigations would be carried out if a fungal infection of the skin is suspected?
o Skin scraping
o Nail clipping
o Hair sample
o Fungal cultures
How are skin biopsies taken?
Punch biopsy
