Dermatology Flashcards
Discuss the role of the skin.
- primary barrier to infection
- physiological - body temperature, fluid balance, vit D synthesis
- sensation of heat, cold, touch and pain
What are the layers of the skin?
Epidermis
Dermis
Subcutaneous
List the layers of the epidermis from superficial to deep.
Stratum corneum
Stratum granulosum
Stratum spinosum
Stratum basale
Give a brief description of the embryology of skin.
- derived from ectoderm
- W5 skin of embryo covered by simple cuboidal epithelium
- W7 single squamous layer and basal layer
- M4 intermediate layer formed
- epidermis invaded by melanoblasts during early foetal period
- hair formed in M3
What is the impact of UV radiation to the skin related to skin cancers?
p53 TGS mutated by DNA damage
Describe the effects of chronic UV exposure.
loss of skin elasticity, fragility, abnormal pigmentation, haemorrhage of blood vessels, wrinkles, premature ageing
Discuss the 4 skin sensation receptors.
- Merkel cells - base of epidermis, sustained gentle and localised pressure, assess shape/edge
- Meissner corpuscles - immediately below epidermis, sensitive to light touch
- Ruffini’s corpuscles - dermis, deep pressure and stretching
- Pacinian corpuscles - deep dermis, deep touch, position/proprioception
What is the aetiology of acne?
- keratin and thick sebum blockage of sebaceous gland
- androgenic increased sebum production and viscosity
- proprioni bacterium inflammation and scarring
Name some clinical features of acne.
- papules
- pustules
- erythema
- comedones
- nodules
- cysts
- scarring
Discuss the treatment options for acne including their side effects.
- Reduce plugging - topical retinoid/benzoyl peroxide. SE = irritant, burning, peeling, bleaching
- Reduce bacteria - topical or oral antibiotics. SE = gastro upset
- Reduce sebum production - antiandrogen e.g. OCP. SE = possible DVT risk
Describe the use of oral isotretinoin in the treatment of severe acne vulgaris.
- concentrated form of vit A
- reduces sebum, plugging and bacteria
- standard course for 16 weeks, 1mg/kg
- SE = mostly trivial. Serious = deranged LFTs, raised lipids, mood disturbance, tertogenicity
- expensive
What is dermatitis?
inflammation of the skin
Name one gene abnormality that may be considered a primary cause of disordered barrier function.
filaggrin (on chromosome 1), proteins which bind to keratin fibres in the epidermal cells
List some endogenous types of dermatitis.
atopic, seborrhoeic, discoid, varicose, pompholyx
List some exogenous types of dermatitis.
contact (allergic, irritant)
photoreaction (allergic, drug)
What is atopic eczema?
itchy inflammatory skin condition associated with asthma, allergic rhinitis, conjunctivitis, hayfever
Which antibody is raised in atopic eczema?
IgE
What are the complications of atopic eczema?
- bacterial infection - Staph. aureus
- viral infection - molluscum, viral warts, eczema herpeticum
- tiredness
- growth reduction
- psychological impact
Describe the management plan of atopic eczema?
- emollients
- topical steroids
- bandages
- sedative antihistamines
- antibiotics/anti-virals
- avoidance of exacerbating factors
- systemic drugs e.g. ciclosporin, methotrexate
- Dupilumab - Il4/13 blocker
How is contact dermatitis precipitated?
irritant - direct noxious effect on skin barrier
allergic - type 4 hypersensitivity reaction
What are some common allergens leading to contact dermatitis
- nickel - jewellery, zips, coins
- chromate - cement, tanned leather
- cobalt - pigment
- colophony - glue, plasters, adhesive tape
- fragrance - cosmetics, creams, soaps
What is seborrhoeic dermatitis? Which areas of the body does it commonly affect?
chronic, scaly inflammatory condition
face, scalp. eyebrows, upper chest
Overgrowth of which organism causes seborrhoeic dermatitis?
Pitryosporum Ovale yeast
Which inflammatory skin disease is often an identifier for HIV?
seborrheoic dermatitis
What is used in the management of seborrhoeic dermatitis?
medicated anti-yeast shampoo, topical antimicrobial and mild steroid, moisturiser
What causes venous dermatitis?
incompetence of deep perforating veins causing increased hydrostatic pressure
Which area of the body is most commonly affected by venous dermatitis?
lower legs
Discuss the management of venous dermatitis?
emollients
topical steroid
compresison bandaging
consider early venous surgical intervention
Define psoriasis.
a chronic relapsing and remitting scaling skin disease which may appear at any age and affect any part of the skin
When does psoriasis often peak?
two peaks
- 20-30 y/o
- 50-60 y/o
Briefly describe the aetiology of psoriasis in three points.
T cell mediated autoimmune disease
Abnormal infiltration of T cells - inflammatory cytokines and keratinocyte proliferation
Environmental and genetic factors
List some conditions linked to psoriasis.
- psoriatic arthritis
- metabolic syndrome
- liver disease/alcohol misuse
- depression
PSORS genes e.g. PSORS1 are associated with which disease?
psoriasis
What are the different types of psoriasis?
- plaque
- guttate
- pustular
- erythrodermic
- flexural/inverse
What is the Koebner phenomenon?
psoriasis at sites of trauma/scars
Describe the appearance of plaque psoriasis.
- raised areas of inflamed skin covered with silvery-white scaly skin
- demarcation
- underlying skin is salmon-pink
Which type of psoriasis appears as ‘teardrop spots’?
guttate
In which group of people does palmar/plantar psoriasis occur?
smokers
Discuss the treatment of psoriasis.
- topical creams and ointments
- phototherapy light treatment
- acitretin
- methotrexate
- ciclosporin
- biological therapies
Which topical therapies are used in the treatment of psoriasis?
- moisturisers
- steroids
- agents which slow down keratinocyte proliferation e.g. vit D analogues
Discuss the role of UV phototherapy in the treatment of psoriasis.
- non-specific immunosuppressant therapy
- can reduce T cell proliferations
- encourages vit D and reduces skin turnover
What are the short and long term risks of UV phototherapy?
short = burning long = skin cancer
Describe two pathways which interact to cause skin cancer.
- Direct action of UV on keratinocytes for neoplastic transformation via DNA damage
- Effects of UV on the host’s immune system
What are the 3 main skin cancer types?
- basal cell carcinoma
- squamous cell carcinoma
- malignant melanoma
PTCH gene mutation may predispose to which skin cancer?
basal-call carcinoma
Where are the majority of BCC found?
head and neck/UV exposed sites
Does BCC metastasise?
rarely
What are the four BCC subtypes?
- nodular
- superficial
- pigmented
- morphoeic/sclerotic
Describe the appearance of nodular BCC.
> 0.5cm raised lesion - shiny, telangectasia, often ulcerated centrally, rolled edge
Which BCC is characterised by superficial proliferation of neoplastic basal cells?
superficial BCC
Why is morphoeic/sclerotic BCC hard to diagnose and manage?
it infiltrates underneath skin at a slow rate, can’t visualise the whole tumour
What is the gold standard treatment of BCC?
surgical excision with 3-4 mm margin
Where does SCC originate from?
keratinocytes
What are the pre-malignant variants of SCC?
- actinic keratoses
- Bowens disease
What is Bowens disease?
SCC in situ
What is the main cause of SCC?
regular exposure to sunlight or other UV radiation
What is the risk of metastasis from a high-risk SCC?
10-30%
What are the high risk sites of SCC?
ears and lips
Describe the appearance of SCC?
- crusty and scaly due to keratin involvement
- slight inflammation
- no shiny rolled margin
What is the gold standard treatment of SCC?
surgical excision 4mm
What is a melanoma?
malignant tumour of melanocytes
Melanoma is most commonly found in the skin. Name two other sites where they can be found?
bowel and eye
Describe the growth pattern of melanoma.
radial growth phase, then vertical growth
How is melanoma spread?
via lymphatics
List some risk factors for developing melanoma.
- genetic markers
- UV radiation
- intermittent burning in unacclimatised fair skin
- immunosuppression
Discuss staging of melanomas in regards to Breslow depth.
5 year survival in non ulcerated tumours is:
- 97% for 0 to 0.1 mm
- 91% for 1.01 to 2.0 mm
- 79% for 2.01 to 4.0 mm
- 71% for > 4.0 mm
What are the medical treatment options for melanoma?
- surgical excision (1-2 cm margin)
- ipilimumab
- MEK inhibitors
Discuss the long term non-medical management of melanoma.
- imaging/scanning
- long term follow-up for 5 years
- assessment for lymph node/organ spread
- genetic testing in families
What is Gorlin’s syndrome?
- multiple BCC
- jaw cysts
- risk of breast cancer
What is Brook Spiegler syndrome?
- multiple BCC
- trichoepitheliomas