Dermatology Flashcards
What are the two main types of skin lesions?
- Melanocytic - tend to be pigmented
- Epidermial (keratinocyte derived) - not pigmented
What are the four basic tumours of epidermal lesions?
Basal cell papilloma
Basal cell carcinoma
Solar/Actinic keratosis
Squamous cell carcinoma
What is the main features of squamous skin tumours?
Sqaoumous cells (everything above the basal layer) - produce keratin
Results in scaly/keratinised lesions.
What are the main skin lesions affecting basal cells?
Benign = basal cell papilloma = seborrheic keratosis
Malignant = basal cell carcinoma
What are the main skin lesions affecting squamous cells?
Benign = solar/actinic keratosis
Malignant = sqaoumous cell carcinoma
What is the most common skin tumour?
Basal cell papilloma = seborrheic keratosis (benign)
What type of skin lesions is this describe?
A solar keratosis
Appears pigmented (although is epidermal in origin)
Raised lesions (from increased amount of keratinocytes)
Warty appearance (lumps and bumps within surface)
Patchy and variable pigmentation
Norm on torso
What are the histological features of solar keratosis?
Cerebrous or warty appearance (bumpy surface)
Containing cysts of keratin - these can be seen on the surface (patchy pigementation)
Looks like a hot cross bun
What are the histological features of basal cell carcinoma?
Grow downwards in islands - however remain attached to overlying abnormal epidermis
Avascular as outgrowths push down blood vessels.
New branching blood vessels may begin to form between outpouching.
What are the gross features of a basal cell carcinoma?
Avascular - pearly or translucent quality
Attempt to grow blood supply - visible larger blood vessels growing in and branching (arborising telangiectasia)
Rolled edges
Central depression/ulceration
What is a development of a basal cell carcinoma?
What is the prognosis?
Ulceration due to avascular centre
The most common cancer in humans.
Does not metastasis
Gradually enlarged locally over the years/months = slow growing
What skin lesion is seen in this image?
Ulcerated BCC
What does Actinic keratosis look like histologically?
Dysplasia of the epidermis
It remains above the basement membrane, with no signs of invasion.
What is the gross appearance of actinic keratosis?
Dysplastic cells produce abnormal keratin - feel hard and spiky.
Looks like green/yellowly scab.
Commonly on areas of maximum sun exposure (back of hands, scalp, temporal, lower lip, top of ears)
What is Bowens Disease?
When epidermal cells are very dysplastic - unable to make keratin - triggers immune response against dysplastic cells.
Grade 3 dysplastic AK lesions - deep lesions
No keratin plaque.
What is a keratin horn?
Feature of a squamous cell skin tumour
The build-up of keratin from dysplastic squamous cells is deposited in a horn-like shape.
What does a cutaneous horn indicate/prognosis?
A squamous tumour of the skin
Typically an benign AK develops into a malignant squamous cell carcinoma (more likely when swelling underneath the horn)
What are the prognostic features of a squamous cell carcinoma of the skill?
Can metastasise
Well differentiated
What are the key diagnostic features of a sqaoumous cell carcinoma on a gross level?
A keratin horn with a lump/swelling underneath - indicated invasion of nearby tissue
Tend to be more rapidly growing - 3 months ish
May be ulcerated
Malignant potential depends on site, histology and size.
How to differentiate between an AK horn and a SCC?
AK - lack of lump - role around between fingers
SCC - lump underneath.
How does a poorly differentiated SCC present?
Nodule of dysplastic cells
Disordered cellular structure - poor blood supply - can ulcerate.
More likely to metastasize than a well differentiated.
What is the main melanocytic tumour of the skin?
Malignant melanoma
What is the prognosis like for malignant melanoma?
Poor prognosis - particularly is deep in skin
No fixed chemotherapy or radiotherapy
One of the largest killers of young people after accidents and suicide.
Metastatic potential depends on Breslow thickness
What features are concerning of malignant melanoma?
New dark flat mole
Young person with many moles - some of which look different
Tends to be pigmented/red
Asymmetrical
Irregular borders
Myriad of colours
What are the key prognostic indicators for Malignant melanoma?
Breslow thickness - for 5yr survival
up to 0.75mm - 98% 5yr
1mm over 90% 5yr
1-3mm 70% 5yr
over 3mm 40% 5yr
What are the key features of malignant melanoma?
Larger moles (compared to others on patient)
Typically a dark black colour (although can become amelanotic)
Asymmetrical - particularly around the edge
ABCD - asymmetry, border, colour and diameter.
What is the difference between a lesion and a rash?
Lesion = one abnormality in one area of the skin
Rash = process, widespread or can affect several areas. Typically red, pimply and itchy.
What is the basic history for a lesion?
Where
How long
Preceding abnormality
Pain etc
UV exposure - pre-cancerous or cancerous lesions:
What is a key part of the UV exposure history?
Tendency to tan/burn - fair/dark skin, freckling
Sun lover or hater
Lived/worked abroad - armed services
Sunbed use
What is the important part of the rash history?
Where did it begin?
How has it evolved?
Previous skin diagnosis?
Sun exposure worsen (lupus) or improve (eczema/psoriasis).
Contact with substances - allergic contact dermatitisis
Occupation/hobbies - allergic
Drugs, when started - drug erruption
Symptoms - itch, pain, weeping (this tends to be eczema)
PMH - atopy (eczema), family (psoriasis or eczema), itchy contacts (scabies)
What are the different levels of the skin?
Epidermis
Dermis
Sub-cutaneous fat
What are the key features of a dermal pathology?
Skin stays smooth
Raised surface
What are the key features of an epidermal pathology?
May or may not be raised
Thickened layers
Surface change - scaly, crusting on surface, fluid seeping through
What are some key terms to use when describing lesions?
Macule - flat and little
Patch - flat and big
Papule - raised and little
Nodule - raised dome shapedand big
Plaque - raised flat
What is a papule?
Raised little lesion
What is a macule?
A flat little lesion
What is a nodule?
A raised large lesion
Dome shaped
What is a patch?
A large flat lesion
What is meant by a vesicle?
Papule (small raised lesion) that is filled with fluid
What is a bulla?
A large raised dome-shaped lesions filled with fluid.
What is a pustule?
A typically small individual skin lesion containing pus.
What is meant by a crust in dermatology?
Dried serum
Orange/yellow colour
May be confused with keratin (normally white/yellow)
Crust must always be removed to reveal underlying pathology as can obscure tumour features.
What is meant by scale in dermatology?
Abnormality of stratum corneum
Accumulation of abnormal keratin
Hyperkeratotic
Build often white, dry deposits
Can be flaked off
What is meant by lichenification & warty process?
Lichenification - scratching of skin causes epidermal thickening - accentuated skin markings (peaks and valleys)
Wart process - rocking up of skin is the warty chain.
What is the difference between erosion, ucler and excoriation?
Erosion - superficial skin loss - exudate visible as crust in surrounding areas
Ulcer - deep loss, all of epidermis and parts of dermis lost
Excoriated - typically from patient scratching
What is meant by purpura in a rash?
Blood leakage in the skin causes a non-blanching dusk purple colour.
How does tissue viability affect the colour of a rash?
Necrosis -> green to black
How does pigment affect the colour of a rash?
Melanin induced - blue or black colour
Pigment due to degraded blood product - hemosiderin - pale brown
Describe this rash?
What is it?
palpable, painful purpura - non-blanching rash.
Cutaneous vasculitis
Tends to be painful and palpable.
May grow to cover larger area and lead to necrosis (due to lack of blood supply to the overlying skin)
Where does psoriasis commonly occur?
Extensors
Where does eczema commonly occur?
Flexural
Why are rashes pimply?
Typically collect lymphocytes/extracellular substances under the epidermis - raise epidermis to form a pimple
What substances can infiltrate the skin and cause a rash?
Inflammatory cells - the majority - lymphocytes, eosinophils and neutrophils.
Extracellular substances - such as pre-tibial myoxoedema.
What does lichen mean related to a rash?
Small bumps on the skin
What are the main types of epidermal rashes?
Eczematous
Psoriasiform
Lichenoid
Vesiculobullous/blistering
What are the different types of dermal rashes?
Vasculopathic
Granulomatous
Tissue deposition.
How does an eczematous rash appear?
Small vesicles in the epidermis - clear cavities on histology (spongiosis) - start small often merge together - variable size blisters.
Keratin may fracture and break off - scaling and dryness
Weeping.
What does a psoriasiform rash?
Vast thickening of epithelium - folds or projections down into dermis
Rough/dry - abnormal keratin - hyperkeratosis/scale
What is a lichenoid rash?
Autoimmune destruction of the bottom of the epidermis
Tend to appear purple grossly
Dermis tends to be replaced by lymphocytes - infiltrate and kill epidermal cells producing colloid bodies
Loss of boundaries between epidermis and dermis
What does a vesiculobullous rash look like?
Fluid-filled swelling
Epidermis separates from dermis - fluid filled space between them
What do vasculopathic rashes look like?
Raised smooth lesions = (hives/urticaria)
Blood vessels - damageed - leaking - blood or fluid - cause purpura or oedema
Histology - band of paleness under epidermis represents oedema.
What do granulomatous rashes look like?
Histology - vast lymphocytes and degrading collagen, granuloma (macrophages arround a centre ring)
Gross - ring-shaped, spread outwards over months, tend to be found on extensor surface of the knuckle.
What does a tissue deposition rash look like?
Scarring and deposition of substance within the dermis.
Collagen proliferation
Gross - brown and waxy appearance, waxy feel on palptation.
What is the basic process of eczema?
Not a disease - a reaction pattern to an insult - any skin at any point
External insults - overwashing, scratching
Internal - skin barrier/cutaneous immune system disorder
What is the typically histological appearance of eczema?
Minute vesicles in the epidermis
This is called spongiosis
May not be visible grossly.
How does eczema present grossly?
Micro vesicles forming larger vesicles on the surface
Vesicles rupture onto surface can burst causing weeping (shininess), large volumes of water loss = dehydration, can dry on surface causing crusts.
Displacement of keratin from underlying vesicles can cause abnormal dryness/flakiness as drops off.
Spectrum from dryness/hyperkeratosis to vesicular (red and weeping)
Where does eczema tend to occur?
On thicker skins -palm of the hands, antecubital fossa, knees
How to tell the difference between the dryness/hyperkeratosis in eczema and psoriasis?
Psoriasis - clear boundary
Eczema - unclear borders, tends to fade in and out of the skin.
What are the different ways of classifying eczema?
Exogenous v endogenous
Acute (weepy) v chronic (dry and scaly) - does not relate to time frame.
What are the different causes of exogenous eczema?
- Contact dermatitis (irritant - chemical in any person such as nappy rash and allergic)
- Photosensitive
- Lichen simplex (scartching)
- Asteatotic - crazy paving (due to dryness of the skin)
What are some different types of contact dermatitis irritant eczema?
Nappy rash - symmetrical, sparing of the creases
Ileostomy - releasing gastric enzymes around stoma - clearly defined circular border
Lip licking eczema - repeated wetness and drying - well defined around mouth (same idea on hands from wetting/drying of hands, shower gels, shampoo, fabric softener, hand soap)
What are some common types of allergic contact eczema?
Elastoplasts
Ear piercing - nickel
Cosmetics and perfume
What are the ways of investigating eczema?
Patch testing
How is patch testing done for eczema?
Why?
Patches of substances on back - what for few days
Tests for Type 4 delayed hypersensitivity
Identifies an allergic contact eczema.
How is the prick test used for skin allergies?
Tests for type 1 immediate hypersensitivity
Immediate response
Produces a urticaria rash
What drugs can predispose patients to photosensitive eczema?
Quinine - used to treat cramp
Thiazide diuretics
What are the different causes of endogenous eczema?
- Atopic eczema - genetic component - e.g filagrin - affects keratin cross-linking.
- Discoid eczema
- Eczema due to venous insufficiency (varicose or venous)
What is discoid eczema?
Legs of older men
Circular-shaped eczema areas - varying in size
What are the key features of atopic eczema?
Thicker skin - elbow flexures, knee, neck
Blistering on palms
Scaliness
Crusting from weeping - notes golden crusts indicate staph. aureus infection.
Glycenation - thickening of skin - increased clarity of skin markings.
What is eczema herpeticulum?
Golden crusts - golden discharge - impetigo
Also many blisters - many popped
Blisters are monomorphic - all the same size
Widespread
Patient often feels very unwell.
Caused by herpes infection.
What is erythroderma?
When more than 95% of the skin is involved in a rash of any kind
May be eczea, psoriasis, drugs, lymphomas, leukaemia or idiopathic.
Serious sign of acute deterioration
requires hospital admission
What is a plaque in dermatology?
A flat raised lesion - large (over 1cm)
What is a wheal in dermatology?
Swelling of the skin into red or skin coloured welts with well defined edges.
What is atrophy in dermatology?
Dimpling/inversion of the skin
Skin still intact.
Localised shrinking of the skin - appears thinner, shiny and wrinkled.
What is meant by a burrow in dermatology?
Commonly seen in scabies
Hole/place of entry
Followed by a red line just under the skin - may be able to see the mite.
What is koebnerization?
Appearance of new lesions that look like patients existing skin disease - often in areas of damage such as scratching.
When handing over what acronym should be used to describe a rash?
Site
Size and shape
Colour
Associated symptoms
Margin & morphology
SCAM
How do you measure breslow thickness for malignant melanomas?
Measured from the epidermis’s granular layer to the tumour’s base.
What is the typical treatment for a basal cell carcinoma?
Excision with 4mm margin
What is the general treatment for a sqaoumous cell carcinoma?
Excision with 4mm margin
What is the general treatment for a malignant melanoma?
Excision with a 2mm margin, followed by a wider excision +/- SLNB.
What are the different types of skin infection?
Bacterial
Viral
Fungal
Infestations
Give some examples of bacterial infections of the skin
Cellulitis - deeper subcutaneous layer
Erysipelas - typically just epidermis/dermis
Impetigo
Menigococcal rash
Chancre
What is the treatment for cellulitisis?
Look for portal of entry
Swabs +/- bloods
Analgesia, fluid, elevation
Manage co-morbs
Oral antibiotics
If severe/systemic - IV antibiotics
Prolonged course may be required.
What is a chancre?
Small painless ulcer
First sign of syphylis
Typically develops on genitals - can also be in the mouth or anus.
Typically followed by red/smallish spots on the palms and soles of the feet.
What are the different viral infections that occur on the skin?
Viral exanthem - widespread, face or trunk alongside generally unwell
Herpes simplex - small vesicle on upper lip
Eczema herpeticulum - infected ulcerated eczema
Zoster virus = shingles
Varicella zoster = chickenpox
What are the different superficial fungal infections that occur on the skin?
Dermatophytes (tinea)
Candida
Other types of yeasts
What does tinea corporis look like?
Fungal infection
Circular, clearly defined, raised scaly edge
Itchy
Trunk or limbs
What do different tinea infections look like in dermatology?
Dry scaly lesions
May have mild eryhthema
Hair loss if relevant
Tine capitis - on the scalp
Tinea pedis - on the foot
Tinea versicolour - loss of pigmentation (asymmetrical - vertiligo is symetrical)
What is onychomycosis?
Tinea unguium
Funal nail infection
Thicker, discoloured and fragmented nail
What is candida intertrigo?
A red itchy rash
Occurs in skin folds when infected by yeast.
What is seborrhoeic dermatitis?
Chronic inflammatory skin disorder
Rash of scaly patches with underlying yellow or white pigments. - erythematous base
Areas of lots of sebaceous glands - around the nose,
What are some infestations that can affect the skin?
Scabies - presents as burrows
Pubic lice
Head lice
Insect bite reaction
What is the treatment for scabies?
5% permethrin cream applied all over skin and left for 8-10hrs
Oral ivermectin 200mcg/Kg
Repeat a week later to kill newly hatched mites
Identify and treat contacts
Launder bed linines, towels and clean rooms
Seal items that cannot be washed in plastic bag for a week
Itching may persist up to 6 weeks.
What are the different types of emollients?
Ointments
Creams
Lotions
What are the pros and cons of creams?
+ Easy to rub in
+ Dont stain clothes
+ will rub into weepy skin
- Not the best moisturisers
- contain preservatives - can cause contact allergy
What are the pros and cons of lotions as emollients?
Mainly water based
- poor moisturisers
+ easy to apply to hairy areas
What are the pros and cons of ointments as emollients?
Better moisturisers than creams
Better for eczema/dry skin
Dont rub in easily
Can be more unwieldy
Can make clothes/sheets messy
Greasy form a waterproof barrier
What are the pros and cons of topical steroids in eczema?
+ range of potencies
+ essientla for all but mildest eczema
+ effective and safe with appropriate use
- toxicity including atrophy (with strong steroids over prolonged periods at the face and skin creases), acne, rarely adrenal suppression.
What are some topical steroids from least to most potent?
Hydrocortison
Eumovate
Betnovate
Dermovate
What is the medical terminology for a mole?
What is this?
A naevus
A local proliferation of melanocytes - congenital or acquired
Develop any time from infancy to early adulthood - more worrying in adults.
What are the different types of moles?
Junctional naevus - melanocytes at DEJ - flat and pigmented
Compound neavus - melanocytes at the DEJ and dermis - central raised areas surrounded by a flat patch
Intradermal naevus - dermis only - raised
How should pigmented lesions be assessed?
ABCDE
Asymmetrical
Borders - uneven?
Colour - two or more?
Diameter - larger than 1/4 inch
Evolving - change size/shape/colour etc
