Introduction to General Dermatology Flashcards
what is the largest organ in the body?
skin
the skin contains what adnexal structures?
(the parts adjoining an organ)
Hair, nails, glands, sensory structures
what are important roles that skin is involved in?
Important role in protection, homeostasis and transmission of sensations
what are the layers of the skin?
3 main layers
Epidermis is the outermost layer and made out of keratinocytes
Melanocytes are the cells that make pigment – everyone has same amount of melanocytes but different amount of melanosomes
Have acquired and innate immune system in the epidermis
Next you have junction attaching epidermis to the dermis
Collagen matrix
No blood vessels in the epidermis and all blood vessels in the dermis
Hair follicles
Erector papillae muscle aswell – Goosebumps for temperature control
Epidermis and dermis is different in different places in your body
It changes a you get older and don’t have same collagen and this is why you get pressure sores etc
Fat layer will be different in different places in the body

what are the layers of the epidermis?

study this picture showing the anatomy of the nail

what are the names of the different stages in the hair cycle?
Anagen
Catagen
Telogen
what happens in the anagen stage of the cell cycle?
active growing phase
80-90% of hair
what happens in the catagen stage of the cell cycle?
2–3 week phase growth stops/follicle shrinks
1–3% of hairs
what happens in the telogen stage of the cell cycle?
resting phase for 1–4 months
up to 10% of hairs in a normal scalp
what are the functions of 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 are the statistics relating to skin disease?
- 22-30% of Population affected
- 15% of consultations in general practice
- 6% of hospital referrals
- 50% skin cancer/lesions
- 25% require surgical procedure
- 10% require patch testing
what percentage of people with a skin problem seek care?

Why is skin disease important?
- Disfigurement
- Discomfort
- Disability
- Depression
- Death
what are the causes of skin disease?
- External - Temperature, UV, chemical (allergen or irritant), infection, trauma
- Internal - Systemic disease, genetics, drugs, infection
what are external causes of skin disease?
Photosensitivity:
- Commonly caused by medications
- Exposed sites affected
- Can be sensitive to UVA, UVB, visible light or a combination of these
Cold Injury:
- Frostbite, Chilblains
- Skin Necrosis
- Cold Urticaria (hives (urticaria) or large red welts form on the skin after exposure to a cold stimulus)
Trauma:
- Dermatitis Artefacta - condition in which skin lesions are solely produced or inflicted by the patient’s own actions

what are internal causes of skin disease?
Genetic
Drug reaction:
- Vary in severity
- Think of OTC drugs
- Take a good history!
Autoimmune:
Bullous Pemphigoid (an autoimmune pruritic skin disease preferentially in elderly people, that may involve the formation of blisters (bullae) in the space between the epidermal and dermal skin layers)

Describing skin lesions:
what is morphology?
Morphology is the appearance of skin lesions
Small usually means less than 5mm
Describing skin lesions:
how do you decribe small and large circumscribed area?
Macule - Small circumscribed area
Patch - Larger circumscribed area
Describing skin lesions:
how do you describe a small and large raised area?
Papule - Small raised area
Plaque - Larger Raised
Describing skin lesions:
how do you describe if it is small or large fluid filled?
Vesicle - Small Fluid filled
Bulla - Large Fluid filled
Describing skin lesions:
how do you describe small and large pus filled?
Pustule - Small Pus filled
Abscess - Large Pus filled
Describing skin lesions:
how do you desribe if it affect the epidermis or dermis?
Erosion - Loss of Epidermis
Ulcer - Loss of Epidermis and dermis
exmaples of skin conditions:


more examples of skin conditions:


what is dermatosis?
a disease of the skin, especially one that does not cause inflammation
what does the distribution of dermatosis mean?
The distribution of a dermatosis refers to how the skin lesions are scattered or spread out
Do skin lesions come as just one or multiple?
Skin lesions may be isolated (solitary or single) or multiple
Do skin diseases have particular distributions?
The localisation of multiple lesions in certain regions helps diagnosis, as skin diseases tend to have characteristic distributions
What is the extent of the eruption and its pattern? - localised, generalised, symmetrical etc
what are the names of some of the most common skin conditions?

the skin in general medicine - cutaneous signs are useful in diagnosing many conditions such a what?
Can diagnose other conditions based off skin conditions
Look at bigger picture as don’t want to miss something else
Take a history to find out if it is just a skin condition or something bigger
Erythema Nodosum
Sarcoidosis
Vasculitis
Malignancy
Auto-immune conditions
what is Acanthosis Nigricans?
Associated with insulin resistance, obesity, malignancy
Flexural distribution
Hyperkeratosis and Hyperpigmentation, papules
‘velvety’ appearance
Doesn’t cause problems
May have undiagnosed type 2 diabetes

what is Thyroid Skin Disease?
Pretibial myxoedema
5% of Graves Disease
Same process as behind eyes – mucinosis
Other skin changes seen in both hyper and hypothyroidism

what investigations would be done in dermatology if bacterial infection was suspected?
- Charcoal swab
- Ask for MC&S
- Microscopy
- Culture
- Sensitivities

what investigations would be done in dermatology if viral infections where suspected?
- Viral swab for PCR
- Can swab vesicle/bulla if vesicular eruption
- If systemic illness, can take throat swab
e.g. chickenpox

what investigations owuld be done in dermatology if fungal infection was suspected?
- Skin scraping
- Nail clipping
- Hair sample
- Fungal cultures

what is a simple way to take a skin biopsy?
punch biopsy
Take lots of biopsies
Around 4 or 5mm
Good for pathology
