Dermatology Flashcards
Name 3 types of skin malignancies
Basal cell carcinoma
Squamous cell carcinoma
Malignant melanoma
Name and describe 3 layers of the skin
Epidermis (thin outer portion of the skin)
Dermis (thicker inner portion of the skin - comprised of connective tissue, nerves, vessels and sweat glands)
Hypodermis (inner most layer - consists of adipose tissue and sweat glands)
What is the most common form of skin cancer?
Basal cell carcinoma
Define basal cell carcinoma
Describes a non-melanoma form of skin cancer.
BCCs develop slowly in the upper layers of the skin and rarely metastasize.
Give 4 risk factors for basal cell carcinoma
Low geographic latitude (i.e Australia)
Low pigment status (fair skin prone to sunburn)
History of skin cancer
Artificial exposure to UV radiation (especially from a young age)
Which skin layer is affected in by basal cell carcinoma?
Basal cell layer of the epidermis
What genes are usually mutated in basal cell carcinoma?
PTCH and TP53
Name 3 types of Basal Cell Carcinoma. Which is the most common?
Nodular (most common)
Superficial
Morpheaform
Give 5 characteristic features of Nodular Basal Cell Carcinomas
Pearly, Shiny Lesions with;
Rolled Borders
Depressed Centre
Small Arborising telangiectasias
Lesions are sensitive and may bleed with minor trauma
Describe the appearance of a Superficial Basal Cell Carcinoma (2)
Presents as a plaque/patch of well defined, scaly, pink skin.
Mostly occur on the trunk and extremities and in younger patients.
What investigations are required for the definitive diagnosis of a basal cell carcinoma?
Punch Biopsy and Histopathological Examination (minimum)
(other biopsies inc - Excisional, Incisional and Shave)
How are low risk BCCs treated? (2)
Complete surgical removal or Electrodesiccation and Curettage
Give 3 possible complications of BCC
Recurrence
Increased risk of other forms of skin cancer
Disfiguration
What is the leading cause of Squamous Cell Carcinoma?
UV exposure (Specifically UVB rays)
Chronic UVB exposure damages the DNA of squamous Keratinocytes, leading to tumour formation.
What gene is commonly mutated in Squamous Cell Carcinoma?
P53 Tumour Suppressor Gene
Give 4 risk factors for Squamous Cell Carcinoma
UV radiation (specifically UVB)
Immunosuppression
Increasing age
Fitzpatrick Skin types I and II (fairer skin)
Give 4 typical physical features of Squamous Cell Carcinoma
Firm to palpate (may be nodular/plaque-like)
May ulcerate and bleed
May be tender or painful
May have crusty keratotic top with a nodular base
Where do squamous cell carcinoma’s tend to appear?
In sun-exposed areas (e.g lips, back of hands, upper part of face or scalp)
Cancerous mutations in which cells causes the formation of squamous cell carcinoma?
In squamous keratinocytes in the epidermis (outermost layer of the skin)
Give 3 differentials in the context of suspected Squamous Cell Carcinoma
Actinic keratosis
Basal Cell Carcinoma
Seborrhoeic Keratosis
Describe Actinic Keratosis
Describes the formation of precancerous scaly lesions on the skin.
Have a 10% risk of developing into SCC, therefore must be monitored and treated accordingly.
How should SSC’s be investigated? What indications are used for each type of biopsy?
Biopsy and histological examination
Excisional or Shave biopsy - Removes whole lesion. Is used if lesion is small, accessible and not in a cosmetically sensitive area.
Incisional/punch biopsy - Used on large lesions as only samples a small (usually 4mm) part of the lesion.
If metastasis of an SCC is suspected, what other investigations is it important to perform? (2)
Ultrasound of Lymph Nodes
CT and MRI for staging or if metastasis is suspected.
Give 4 indicators of a poor prognosis for squamous cell carcinoma
Poorly differentiated tumours (histologically)
> 20mm in diameter
> 4mm deep
Patient is immunosuppressed
How are squamous cell carcinomas managed?
2 week wait for potential SCCs to a skin cancer screening clinic
Surgical excision with 4mm margins if lesion is <20mm in diameter
Surgical excision with 6mm margins if lesion is >20mm in diameter.
Describe Bowen’s Disease
Describes a type of precancerous dermatosis that is a precursor to squamous cell carcinoma.
Commonly seen in elderly patients
What are the 1st line managements for Bowen’s disease?
Topical 5-fluorouracil
Cryotherapy
What may be used as primary and secondary prevention of squamous cell carcinoma? (4)
UV-A and UV-B coverage suncreams
Avoidance of sun
Discouraging the use of sunbeds
Physical sun protection
Describe Malignant Melanoma
Describes a malignant cancer that arises from the melanocyte layer of the skin, normally situated in the basal layer of the epidermis
State 3 ways in which the growth of a melanoma can be described
In situ - Tumour is confined to epidermis
Invasive - Tumour has spread into the dermis
Metastatic - Tumour has spread to other tissues
What may form when melanocytes grow in a non-cancerous way?
Moles and freckles
Name 2 subtypes of melanoma. Which is the most common? Which is the most aggressive?
Superficial spreading melanoma (most common)
Nodular melanoma (most aggressive)
Describe the clinical features of a melanoma using the ABCDE criteria.
A - Asymmetrical Shape
B - Border irregularity (inc poorly defined margins)
C - Colour change and variation
D - Diameter of the mole (>6mm)
E - Evolving (changing in size, shape or colour)
List 3 main diagnostic features (major criteria) fo melanoma
Relating to previous Mole;
Change in Size
Change in Shape
Change in Colour
List 4 secondary features of melanoma (minor criteria)
Diameter >=7mm
Inflammation
Oozing or bleeding
Altered sensation
Give 3 differentials for a pigmented lesion
Benign naevus (mole)
Seborrhoeic keratoses
Pigmented basal cell carcinoma
What is used to investigate malignant melanoma?
Visualisation using a Dermatoscope
Skin biopsy - Confirms diagnosis
What scoring system is the most important factor for determining prognosis of patients with malignant melanoma?
Breslow Depth (invasion depth of a tumour)
What is the definitive management of malignant melanoma?
Surgical excision of tumour and margins.
Describe Urticaria. What is it also known as?
Describes a pale, pink, pruritic raised rash.
AKA hives, wheals or nettle rash
Name 4 drug classes known to cause urticaria
Aspirin
Penicillin’s
NSAIDs
Opiates
How is Urticaria Managed? (3)
Non sedating antihistamines - Loratadine/Cetirizine for 6 weeks
Sedating Antihistamine - Chlorphenamine (at night time for sleep symptoms)
Prednisolone - Used for severe or resistant episodes
Give 3 causes of acute urticaria
Allergies to foods, medications or animals
Contact with chemicals, latex or stinging nettles
Viral infections
Give 3 forms of chronic urticaria
Chronic Idiopathic Urticaria (recurrent episodes with no clear cause/trigger)
Chronic Inducible Urticaria (episodes induced by a trigger)
Autoimmune urticaria (Associated with autoimmune diseases, such as SLE)
Give 4 possible triggers of Chronic Inducible Urticaria
Sunlight
Temperature Change
Exercise
Strong emotions
Describe impetigo
Describes a superficial bacterial skin infection caused by Staphylococcus Aureus or Streptococcus Pyogenes.
Where does impetigo tend to manifest?
Can develop anywhere.
Tends to manifest on face (around lips), flexures and limbs not covered by clothing.
How is impetigo spread?
Spread by direct contact with discharges from the scabs of an infected person.
Bacteria invade skin through minor abrasions and then spread to other sites by scratching.
What is the incubation period for impetigo?
4 to 10 days
How is impetigo managed in people who are not systemically unwell or at high risk of complications?
Hydrogen peroxide 1% cream
What oral antibiotic is used to treat wise spread or severe impetigo?
Oral Flucloxacillin
(Oral erythromycin if penicillin allergy)
What topical antibiotic cream can be used to treat impetigo?
Topical Fusidic Acid.
For how long should children with impetigo be excluded from school?
Until lesions are crusted and healed OR 48 hours after commencing antibiotic treatment.
Describe cellulitis
Describes an infection of the skin and the deeper subcutaneous tissues.
What pathogen most commonly causes cellulitis?
Streptococcus pyogenes
What is it important to look for when examining a patient with cellulitis?
A breach in the skin. As this will be the point of entry for the bacteria
(may be due to skin trauma, eczema, fungal nail infections or ulcers)
Give 4 clinical features of cellulitis (specifically regarding skin changes)
Skin changes include;
Erythema (red discolouration)
Warm or hot to touch
Oedematous
Bullae (fluid-filled blisters)
What clinical skin feature may suggest cellulitis due to Staphylococcus aureus infection rather than Streptococcus pyogenes?
A golden-yellow crust.
What life-threatening complication can occur as a result of cellulitis?
Sepsis (suspect if patient is systemically unwell)
What criteria is used to assess the severity of cellulitis?
Eron Classification
How is cellulitis diagnosed?
Clinical diagnosis.
Conduct bloods and blood cultures of sepsis is suspected.
When treating cellulitis, in whom are IV antibiotics indicated? (6)
Eron Class III or IV cellulitis
Severe or rapidly deteriorating cellulitis
Very young (<1) or frail
Immunocompomised
Has significant lymphoedema
Has facial cellulitis or periorbital cellulitis
What oral antibiotics are given to manage Eron Class I and II?
1st line - Oral Flucloxacillin
2nd - Oral Clarithromycin, Erythromycin (in pregnancy) or Doxycycline (if penicillin allergy)
How is Eron Class III-IV cellulitis managed?
Admit
Oral/IV co-amoxiclav/clindamycin/cefuroxime or ceftriaxone
What is the 1st line antibiotic for cellulitis near the eyes or nose?
Co-amoxiclav
Describe eczema. Where does it tend to present?
Describes a chronic atopic condition caused by defects in the normal continuity of the skin barrier, leading to inflammation in the skin.
Presents during infancy with dry, red, itchy and sore patches of skin over the flexor surfaces (inside elbows and knees) and on face and neck.
How does eczema tend to behave?
Patients experience periods where the condition is well controlled and periods where the eczema is more problematic, known as flares.
How is eczema managed? (4)
Avoid irritants
Simple emollients (create an artificial barrier over the skin)
Wet wraps (cover area with thick emollient and wrap to keep mositure locked in overnight)
Topical steroids (weakest steroid for the shortest period)
How often should emollients be used in patients with eczema?
Use as often as possible, particularly after washing and before bed.
What can be used to treat severe cases of eczema?
Ciclosporin (DMARD)
Describe a the steroid ladder from weakest to most potent. Give examples
Mild - Hydrocortisone
Moderate - Eumovate
Potent - Betnovate
Very potent - Dermovate
What bacteria most commonly invades skin in eczema? What is used to treat this infection?
Staphylococcus aureus.
Flucloxacillin
Name 1 severe complication of eczema and describe it’s cause
Eczema herpeticum
Caused by Herpes Simplex Virus 1 (or 2)
How may Eczema Herpeticum present? (3)
Widespread, painful vesicular rash
Systemic symptoms; fever, lethargy, irritability
Lymphadenopathy
How is Eczema Herpeticum investigated?
Viral swabs - Confirm diagnosis
How is Eczema Herpeticum managed?
Mild to moderate disease - Oral Aciclovir
Severe disease - IV aciclovir
Give 1 complication of eczema herpeticum
Bacterial superinfection, leading to more severe illness.
What is the name of the mite that causes scabies?
Sarcoptes scabiei
How is scabies spread?
Prolonged skin contact
Where in the skin does the scabies mite lay it’s eggs?
Striatum corneum
What causes the intense pruritus associated with scabies?
A delayed type IV hypersensitivity reaction to mites/eggs which occurs 30 days after the initial infection
Give 3 clinical features of scabies
Widespread pruritus
Linear burrows on the side of fingers, interdigital webs and flexor aspects of the wrists
Excoriation or infection secondary to scratching.
What is the 1st and 2nd line treatment for scabies?(2)
1st line - Permethrin
2nd line - Malathion
For how long can scabies induced pruritus persist post eradication?
4-6 weeks
What additional advice should be given to patients being treated for scabies?
Avoid close physical contact with others until treatment is complete
All household and physical contacts should receive treatment, even if asymptomatic
Launder, iron and tumble dry clothing, bedding and towels on 1st day of treatment to kill of mites
What variation of scabies is seen in HIV? and how is it treated?
Crusted scabies
Treated with Ivermectin
What parasitic insect commonly causes headlice?
Pediculus capitis
How long does it take for headlice eggs to hatch?
7-10 days
How is headlice spread?
Direct head-to-head contact
How is headlice diagnosed?
Fine-toothed combing of wet or dry hair
How is headlice managed?
Treatment is only indicated if living lice are found.
Wet combing
Malathion
Do household contacts of patients with headlice need treatment?
No, unless they are also affected
Do children with headlice require school exclusion?
No
What type of hypersensitivity reaction is allergic contact dermatitis?
Type 4 Hypersensitivity Reaction
What test can be used to determine an allergic contact dermatitis?
Patch testing in response to a specific allergen
Name 2 types of contact dermatitis
Irritant contact dermatitis (most common - Often seen in hands due to weak acids of alkalis, e.g detergents)
Allergic contact dermatitis (uncommon - often seen in head following hair dyes)
Acne vulgaris is caused be chronic inflammation in pockets of skin known as what? Describe these/
Pilosebaceous units
Describes tiny dimples in the skin containing hair follicles and sebaceous glands. The sebaceous glands produce natural skin oils and a waxy substance known as Sebum.
Describe the pathophysiology of Acne
Chronic inflammation of pilosebaceous units > increased production of sebum > trapping of keratin (dead skin cells) > Blockage of pilosebaceous units > Swelling and inflammation.
Why is acne exacerbated by puberty and improves with anti-androgenic hormonal contraception?
Androgenic hormones increase the production of sebum.
What is the name of swollen and inflamed pilosebaceous units?
Comedones
Colonisation of which anaerobic bacterium plays an important role in acne?
Propionibacterium acnes.
Treatments of acne aim to reduce these bacteia
Name 4 different types of acne lesions which can be seen in a patient with acne
Comedones (Whiteheads and Blackheads)
Papules and Pustules - Moderate inflammation
Nodules and Cysts - Excessive inflammation
Ice-pick and hypertrophic scars - Scarring
Define mild acne
Mild = Open and Closed comedones with or without sparse inflammatory lesions
Define moderate acne
Moderate - Widespread non-inflammatory lesions and numerous papules and pustules
Define severe acne
Extensive inflammatory lesions, which may include nodules, pitting and scaring
How is mild to moderate acne treated?
12 week course of topical combination therapy;
Topical adapalene + Topical benzoyl peroxide
Topical tretinoin + Topical clindamycin
Topical benzoyl peroxide + Topical clindamycin
Can topical benzoyl peroxide be used as a monotherapy if other medications are contraindicated?
Yes
What class of drugs are Adapalene and Tretinoin?
Topical retinoids
How is moderate to severe asthma managed?
12 week course of topical combination therapy;
Topical adapalene + Topical benzoyl peroxide
Topical tretinoin + Topical clindamycin
Topical adapalene + topical benzoyl peroxide + either oral lymecycline or oral doxycycline
What should be offered to treat acne in pregnancy instead of tetracyclines?
Erythromycin
What should always be co-prescribed with a oral antibiotics to reduce the risk of antibiotic resistance developing? (in acne)
Topical retinoid or benzoyl peroxide
What is the final line treatment for acne?
Oral isotretinoin
To reduce risk of antibiotic, name 3 treatment strategies that should NOT be used.
Monotherapy with topical antibiotic
Monotherapy with oral antibiotic
A combination of topical antibiotic and an oral antibiotic.
How does topical benzoyl peroxide treat acne?
Reduces inflammation
Helps unblock the skin
Is toxic to P.acnes bacteria
How to topical retinoids treat acne?
Slow the production of sebum
Give 4 side effects of Isotretinoin
Strongly teratogenic (avoid in pregnancy)
Photosensitivity of skin to sunlight
Dry skin and lips
Steven-Johnson syndrome (rarely)
Give 4 features of Rosacea
Flushing (first symptom)
Telangiectesia
Persistent erythema with papules and pustules
Sunlight may exacerbate symptoms
What may exacerbate symptoms of Rosecea?
Sunlight
What is typically the 1st presenting symptom of Rosecea?
Flushing
What is used to manage erythema/flushing in rosecea
Topical brimonidine (alpha adrenergic agonist)
What is used to treat mild to moderate rosecea with papulaes and/or pustules?
Topical Ivermectin
What is used to treat moderate to severe rosecea?
Combination topical ivermectin + oral doxycycline
