Introduction to dermatology Flashcards
What are the layers of the epidermis? (5)
From superficial to deep: Stratum corneum Stratum lucidum Stratum granulosum Stratum spinosum Stratum basale
What are Langerhans cells?
Part of the dendritic cell family
They are involved in antigen presentation (process them) and they migrate to lymph nodes to induce an immune response
What are the 3 layers of skin called?
Epidermis
Dermis
Subcutaneous tissue (hypodermis)
Function of subcutaneous tissue
Fat energy store
Insulation
Fibrous bands anchor skin to fascia
What does the dermis contain?
Contains nerve endings Oil Sweat glands Hair follicles Also has fibroblasts, dermal dendritic cells and macrophages
What are melanocytes
Cells located in the stratum basale that make melanosomes (collections of melanin).
These are excreted and phagocytosed into keratinocytes where they sit above the nucleus
What is the active hair growing phase called?
Anagen
80-90% of hair
What happens in the Catagen phase in the hair cycle
2-3 week phase where growth stops/follicle shrinks
1-3% of hairs
Telogen phase of hair cycle
Resting phase for 1-4 months
up to 10% of hairs in a normal scalp
Functions of the skin (6)
Thermoregulation Skin immune system Barrier Sensation - temp/touch/pain Vit D synthesis Interpersonal communication
How does skin act as a barrier?
Protects against Mechanical, Chemical, microorganisms, UV light
Keeps in water and Electrolytes, Macromolecules
How does the skin synthesise Vitamin D?
UV light converts 7-dehydrocholesterol to cholecalciferol
What is meant by interpersonal communication
Your physical appearance, smell and self identity
What % of derm patients are in primary vs secondary care
3% see a dermatologist
17% are looked after in primary care
80% don’t see any doctor about their problem
Importance of skin disease? The 5 D’s
Disfigurement Discomfort Disability Depression Death
External causes of skin disease (5)
Temperature UV Chemical (allergen or irritant) Infection Trauma
Internal causes of skin disease (4)
Systemic
Genetics
Drugs
Infection
What is Photo-sensitivity?
An extreme sensitivity to UVA, UVB, visible light or a combination of these
Commonly caused by medications
Exposed sites affected
Difference between UVA and UVB?
Ultraviolet A (UVA) has a longer wavelength, and is associated with skin aging.
Ultraviolet B (UVB) has a shorter wavelength and is associated with skin burning.
Cold injuries to the skin (4)
Frostbite
Skin necrosis
Cold urticaria
Chillblains - small lesions caused by the inflammation of tiny blood vessels after exposure to cold air
What is cold urticaria?
hives (urticaria) or large red welts form on the skin after exposure to a cold stimulus
What is Bullous Pemphigoid?
An autoimmune skin disease - may form blisters
Define the term ‘Macule’
Small circumscribed (confined) area
Define the term ‘Patch’
Larger circumscribed area
Define the term ‘Papule’
Small raised area
Define the term ‘Plaque’
Larger raised area
Define the term ‘Vesicle’
Small fluid filled
Define the term ‘Bulla’
Large fluid filled
Define the term ‘Pustule’
Small pus filled
Define the term ‘Abscess’
Large pus filled
Define the term ‘Erosion’
Loss of epidermis
Define the term ‘Ulcer’
Loss of epidermis and dermis
What are the most common skin conditions (10)
Acne Psoriasis Rosacea Skin lesions Urticaria Warts Leg ulcers Scalp/nail disorders Eczema Infections/infestations
Eruptive xanthoma can be caused by which condition
Hyperlipidaemia
What is Acanthosis Nigricans
A brown to black, poorly defined, velvety hyperpigmentation of the skin. It is usually found in body folds (flexural disrtibution)
Associated with insulin resistance, obesity or malignancy
Thyroid skin disease
Pretibial myxoedema
5% of Grave’s disease
Same process occurs behind the eyes - mucinosis
What investigations can be done if a bacterial skin infection is suspected (2)
Charcoal swab
Microscopy, culture and sensitivity (MC&S)
What investigations can be done if a viral skin infection is suspected (3)
Viral swab for PCR
Can swab vesicle/bulla if vesicular eruption
If systemic illness, can take throat swab
What investigations can be done if a fungal skin infection is suspected (4)
Skin scraping
Nail clipping
Hair sample
Fungal cultures
