Dermatology

Question 1

What are the 3 main layers of the skin?

Answer 1

-epidermis
-dermis
-subcutaneous tissue

Question 2

What is the function of the skin?

Answer 2

Epidermis acts a protective barrier, protects from bacteria etc

Question 3

What is the stratum corneum?

Answer 3

Outer keratin layer of the epidermis

Question 4

Where is stratum corneum thicker?

Answer 4

Palms of hand
Soles of feet

Question 5

Why does psoriasis present with plaques?

Answer 5

Increased cell turnover
Hyper proliferation of epidermis

Question 6

How can acne vulgaris be classified?

Answer 6

mild: open and closed comedones with or without sparse inflammatory lesions

moderate acne: widespread non-inflammatory lesions and numerous papules and pustules

severe acne: extensive inflammatory lesions, which may include nodules, pitting, and scarring

Question 7

What’s the treatment for mild-moderate acne vulgaris?

Answer 7

-12wk topical combination therapy:

-a fixed combination of topical adapalene with topical benzoyl peroxide
-a fixed combination of topical tretinoin with topical clindamycin
-a fixed combination of topical benzoyl peroxide with topical clindamycin

topical benzoyl peroxide may be used as monotherapy if these options are contraindicated

Question 8

What’s the treatment for moderate to severe acne vulgaris?

Answer 8

12-week course of one of the following options:
-a fixed combination of topical adapalene with topical benzoyl peroxide
-a fixed combination of topical tretinoin with topical clindamycin
-a fixed combination of topical adapalene with topical benzoyl peroxide + either oral lymecycline or oral doxycycline
-a topical azelaic acid + either oral lymecycline or oral doxycycline

tetracyclines should be avoided in pregnant or breastfeeding women and in children younger than 12 years of age

Question 9

What is the pathophysiology of acne vulgaris?

Answer 9

-follicular epidermal hyperproliferation, leading to formation of keratin plug, causes obstruction of pilosebaceous follicle.

Colonisation by anaerobic bacterium Propionibacterium acnes

Inflammation

Activity of sebaceous glands controlled by androgen, why acne often starts during puberty

Question 10

What is actinic keratoses?

Answer 10

premalignant skin lesion that develops as a consequence of chronic sun exposure

Question 11

What is the typical appearance of actinic keratoses?

Answer 11

small, crusty or scaly, lesions

may be pink, red, brown or the same colour as the skin

typically on sun-exposed areas e.g. temples of head

multiple lesions may be present

Question 12

What are some management options for actinic keratoses?

Answer 12

Sun avoidance and sun cream

fluorouracil cream: typically a 2 to 3 week course

topical diclofenac

cryotherapy

curettage and cautery

Question 13

What is Acanthosis nigricans?

Answer 13

Describes symmetrical, brown, velvety plaques that are often found on the neck, axilla and groin

Question 14

What is the pathophysiology of acanthosis nigricans?

Answer 14

insulin resistance → hyperinsulinemia → stimulation of keratinocytes and dermal fibroblast proliferation via interaction with insulin-like growth factor receptor-1 (IGFR1)

Question 15

What are some causes of acanthosis nigricans?

Answer 15

obesity
type 2 diabetes mellitus
polycystic ovary syndrome
Cushing’s syndrome
acromegaly
hypothyroidism
familial
Prader-Willi syndrome
gastrointestinal cancer
drugs
combined oral contraceptive pill
nicotinic acid

Question 16

Whats an example of a sedating anti-histamine?

Answer 16

chlorpheniramine

Question 17

Give example of non sedating anti-histamine?

Answer 17

loratidine
cetirizine

Question 18

What should be done if BCC if suspected?

Answer 18

Routine referral to dermatology, 2wk wait isnt required

Question 19

What are some management options for BCC?

Answer 19

surgical removal

curettage

cryotherapy

topical cream: imiquimod, fluorouracil

radiotherapy

Question 20

What are some features of BCC?

Answer 20

sun-exposed sites, especially the head and neck account for the majority of lesions

initially a pearly, flesh-coloured papule with telangiectasia
may later ulcerate leaving a central ‘crater’

Question 21

What is thr character of BCC?

Answer 21

slow-growth and local invasion

Metastases are extremely rare

Question 22

What type of hypersensitivity is allergic contact dermatitis?

Answer 22

Type VI

Question 23

What is dermatitis herpetiformis?

Answer 23

an autoimmune blistering skin disorder associated with coeliac disease

deposition of IgA in the dermis

Question 24

What are some features of dermatitis herpetiformis and how is it diagnosed?

Answer 24

itchy, vesicular skin lesions on the extensor surfaces (e.g. elbows, knees, buttocks)

skin biopsy: direct immunofluorescence shows deposition of IgA in a granular pattern in the upper dermis

Question 25

What’s the management for dermatitis herpetiformis?

Answer 25

gluten-free diet dapsone - antibiotic with anti-inflammatory properties

Question 26

What is Eczema herpeticum?

Answer 26

Emergency severe primary infection of the skin by herpes simplex virus 1 or 2 more commonly seen in children with atopic eczema and often presents as a rapidly progressing painful rash.

Question 27

What’s the appearance of eczema herpeticum?

Answer 27

monomorphic punched-out erosions (circular, depressed, ulcerated lesions) usually 1-3 mm in diameter are typically seen

Question 28

What’s the treatment for eczema herpeticum?

Answer 28

IV aciclovir

Question 29

What topical steroid is ‘mild’?

Answer 29

Hydrocortisone 0.5-2.5%

Question 30

What topical steroid is moderate?

Answer 30

Betnovate (betamethasone Valerate 0.025%) Eumovate

Question 31

What topical steroids are ‘potent’?

Answer 31

Cutivate 0.05% Betnovate 0.1%

Question 32

What topical steroid is ‘very potent’?

Answer 32

Dermovate 0.05%

Question 33

What is erythema multiforme?

Answer 33

hypersensitivity reaction that is most commonly triggered by infections

Question 34

What are some features of erythema multiforme?

Answer 34

target lesions initially seen on the back of the hands / feet before spreading to the torso upper limbs are more commonly affected than the lower limbs pruritus is occasionally seen and is usually mild

Question 35

What are some causes of erythema multiforme?

Answer 35

viruses: herpes simplex virus (the most common cause), Orf* idiopathic bacteria: Mycoplasma, Streptococcus drugs: penicillin, sulphonamides, carbamazepine, allopurinol, NSAIDs, oral contraceptive pill, nevirapine connective tissue disease e.g. Systemic lupus erythematosus sarcoidosis malignancy

Question 36

What is impetigo?

Answer 36

superficial bacterial skin infection usually caused by either Staphylcoccus aureus or Streptococcus pyogenes

Question 37

What are some features of impetigo?

Answer 37

'golden', crusted skin lesions typically found around the mouth very contagious Spread is by direct contact with discharges from the scabs of an infected person indirect spread via toys, clothing, equipment and the environment may occur The incubation period is between 4 to 10 days.

Question 38

What’s the management for impetigo?

Answer 38

Limited local disease: -hydrogen peroxide 1% cream -topical antibiotic creams Extensive disease: -oral flucloxacillin -oral erythromycin if pen allergic Stay of school until lesions crusted and healed, or 48hrs after starting Abx

Question 39

What are the four main subtypes of melanoma?

Answer 39

Superficial spreading (most common) Nodular Lentigo maligna Acral lentiginous

Question 40

What are the main diagnostic and secondary features for diagnosis melanoma?

Answer 40

Main: Change in size Change in shape Change in colour Secondary: Diameter >= 7mm Inflammation Oozing or bleeding Altered sensation

Question 41

What is psoriasis?

Answer 41

Chronic skin disorder red, scaly patches on the skin

Question 42

What are some features of psoriasis?

Answer 42

well-demarcated red, scaly patches affecting the extensor surfaces, sacrum and scalp nail signs: pitting, onycholysis arthritis

Question 43

What are some complications of psoriasis?

Answer 43

psoriatic arthropathy (around 10%) increased incidence of metabolic syndrome increased incidence of cardiovascular disease increased incidence of venous thromboembolism psychological distress

Question 44

What are some factors that may exacerbate psoriasis?

Answer 44

trauma alcohol drugs: beta blockers, lithium, antimalarials (chloroquine and hydroxychloroquine), NSAIDs and ACE inhibitors, infliximab withdrawal of systemic steroids Streptococcal infection may trigger guttate psoriasis

Question 45

What is the management of psoriasis?

Answer 45

Stepwise approach Regular emollients 1st line - potent corticosteroid + vit D analogue daily up to 4wks 2nd line - if no improvement after 8wks, vit D analogue twice daily 3rd line - no improvement after 8-12wks, potent corticosteroid twice daily 4wks OR coal tar prep 1-2 a day

Question 46

What systemic therapy can be used in psoriasis?

Answer 46

oral methotrexate is used first-line. It is particularly useful if there is associated joint disease ciclosporin systemic retinoids biological agents: infliximab, etanercept and adalimumab ustekinumab (IL-12 and IL-23 blocker) is showing promise in early trials

Question 47

What is seborrhoeic keratoses?

Answer 47

benign epidermal skin lesions seen in older people large variation in colour from flesh to light-brown to black have a 'stuck-on' appearance keratotic plugs may be seen on the surface

Question 48

What is shingles?

Answer 48

Shingles (herpes zoster infection) is an acute, unilateral, painful blistering rash caused by reactivation of the varicella-zoster virus (VZV) Following primary infection with VZV (chickenpox), the virus lies dormant in the dorsal root or cranial nerve ganglia

Question 49

What are some risk factors for shingles?

Answer 49

increasing age HIV: strong risk factor, 15 times more common other immunosuppressive conditions (e.g. steroids, chemotherapy)

Question 50

What are some features of shingles?

Answer 50

Most affected dermatomes T1-L2 prodromal period burning pain over the affected dermatome for 2-3 days pain may be severe and interfere with sleep around 20% of patients will experience fever, headache, lethargy rash initially erythematous, macular rash over the affected dermatome quickly becomes vesicular characteristically is well demarcated by the dermatome and does not cross the midline. However, some 'bleeding' into adjacent areas may be seen

Question 51

What’s the management for shingles?

Answer 51

may need to avoid pregnant women and the immunosuppressed should be advised that they are infectious until the vesicles have crusted over, usually 5-7 days following onset Analgesia recommend antivirals within 72 hours for the majority of patients, unless the patient is < 50 years and has a 'mild' truncal rash associated with mild pain and no underlying risk factors - aciclovir, famciclovir, or valaciclovir

Question 52

What are some risk factors for SSC?

Answer 52

excessive exposure to sunlight / psoralen UVA therapy actinic keratoses and Bowen's disease immunosuppression e.g. following renal transplant, HIV smoking long-standing leg ulcers (Marjolin's ulcer) genetic conditions e.g. xeroderma pigmentosum, oculocutaneous albinism

Question 53

What are some features of SSC?

Answer 53

typically on sun-exposed sites such as the head and neck or dorsum of the hands and arms rapidly expanding painless, ulcerate nodules may have a cauliflower-like appearance there may be areas of bleeding

Question 54

What’s the treatment for SSC?

Answer 54

Surgical excision with 4mm margins if lesion <20mm in diameter. If tumour >20mm then margins should be 6mm