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33 Cards in this Set

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Which UV wavelengths damage which layers of the skin and how?

UV-A - to the dermis - ageing and wrinkling


UV-B - to the skin surface - Burning

How does UV directly damage DNA?

Produces thymidine dimers

How does UV indirectly damage DNA?

Creates free radicals leading to oxidative DNA damage

Why is skin cancer so common in the UK?

Tanning and sunbeds, lack of sun cream

What causes benign moles (melanocytic nevi)

Congenital or acquired


More common in sun exposed areas

What are the ABCDE's of moles?

Asymmetry


Border


Colour


Diameter


Evolving

What is a melanoma?

Tumour of the melanocyte


50% from existing moles, 50% from normal skin

What are some intrinsic risk factors for melanomas?

Fair skin - melanin levels


Many/atypical moles - increased melanocyte conc


Fx - CDKN2A-p16 tumour suppressor gene

What is the most common melanoma?

Superficial spreading melanoma

What does a superficial spreading melanoma look like and what causes it?

Grow in horizontal growth phase like a puddle


Can invade and spread


Intermittent sun exposure

What is a Lentigo Maligna Melanoma

Primarily grow in horizontal growth phase like a puddle


Rarely invade and spread


Continuous sun exposure

What is a Nodule Melanoma

Primarily grown in vertically


Burrowing mole


Frequently invade and spread

What is a Nail Melanoma?

Grow both horizontally and vertically


Frequently ignored and misdiagnosed by pts


Frequently invade and spread

What is an Amelanotic melanoma?

Grow mainly vertically


Frequently misdiagnosed and ignored by pts


Frequently invade and spread

What are some typical melanoma mimics?

Dysplastic melanocytic nevus - benign moles


Seborrheic keratosis - waxy, scaly, slightly elevated, cause not known (not thought to be sun induced)


Solar lentigo - harmless patch of darkened skin, excessive melanin


Dermatofibroma - benign fibrous nodule, reaction to insect bites

Treatment and outcome for non-invasive melanoma?

Surgical excision - 98% curative

Treatment and outcome for invasive melanoma?

Pharmacological intervention - 18% 5ys




Radiotherapy/dacarbazine or B-raf inhibitors

What is the presentation of atopic dermatitis (eczema)?

Acute skin rash (red, dry, itchy)


Typically presents on flexor surfaces, exposed skin



What type of disorder is eczema?

Hypersensitivity disorder

What is the mechanism of action of eczema?

Inflammation due to allergen makes skin 'leaky'


Allows in more of the allergen


Allows more water to escape


Skin becomes dry and itchy/damaged




Leads to a cycle of scratching > allergy mediated inflammation > dry skin

Clinical consequences of eczema?

Recurrent infections


Cellulitis


Sleep disturbances


Painful movement


Anxiety


Depression


Cardiovascular issues

What causes Cellulitis?

Typically group A strep but all staph

What is Psoriasis?

Chronic skin plaque (red, flaky, crusty) covered by silvery scales


Elbows, knees, scalp, lower back




Cause not fully known by also hypersensitivity disorder

Mechanism of action of psoriasis?

1) Promoted keratinocyte cell growth


2) H2O leak


3) Immune mediation leads to dilated vessels bringing in more immune cells

Clinical consequences of Psoriasis?

Recurrent infections


Sleep disturbances


Inhibited movement


Anxiety


Depression


Cardiovascular




25% developed psoriatic arthritis

Treatment for psoriasis?

Topical corticosteroids - reduce inflammation


Phototherapy - UV light kills hyperactivated lymphocytes

What is Actinic Keratosis?

Precursor lesion to squamous cell carcinoma


Risk factor - Chronic sun exposure

Treatment for Actinic Keratosis?

Pharmacological intervention - imiquimod - 99% cure


Untreated - 0.5% py progress to squamous cell carcinoma

What is Squamous Cell Carcinoma?

2nd most common type of skin cancer


Risk factor - long term sun exposure and immunocompromised

Treatment for Squamous Cell Carcinoma?

Non-invasive - Excision 99% cure


Untreated - 0.5%py progress to invade/spread




Invasive - Chemo - 15% 5yr survival

What is Basal Cell Carcinoma?

Most common type of skin cancer


Risk factor - intermittent sun exposure




Nodular, superficial and infiltrative BCC

Treatment for BCC?

Excision 99% cure


Invasion is extremely rare


True invasion of infiltrative is <0.5%


Sonic Hedgehog inhibitor for for infiltrative