Dermatology

Question 1

List two methods to differentiate between benign and malignant skin cancer

Answer 1

ABCDE Rule:

• Asymmetric
• Borders are irregular
• colours are multiple
• Diameter >6mm
• Evoluation in colour, size or shape over short time

7 Point Checklist:

• Major Criteria (2 points): change in size, irregular shape, irregular colour
• Minor criteria (1 point): largest diameter >=7mm, inflammation, oozing, change in sensation

Question 2

List the risk factors for skin cancer

Answer 2

no SPF is a SIN

• Sun exposure
• pigment traits (blue eyes, fair/red hair, pale complexion)
• freckling
• skin reaction to sunlight
• immunosuppressant
• nevi

Question 3

Discuss the presentation and management of basal cell carcinoma

Answer 3

Pathophysiology: arises from the basal cells, least aggressive
Presentation: nodulo-ulcerative type
- papule/plaque/nodule with white translucent shiny scale
- well defined borders
- telengectasia
Management:
- superficial on trunk: imiquimod
- face: Mohs excision
- shave excision + electrodissection and currettage

Question 4

Discuss the presentation and management of squamous cell carcinoma

Answer 4

Pathophysiology: arises from the supra-basalar stem cells in epidermis
Presentation: 
- indurated, erythematous nodule/plaque with surface crust 
- eventually ulcerated
- more scales
- volcano morphology
Location: face, ears, scalp, forearms
Management: surgical excision

Question 5

Discuss the presentation and management of melanoma

Answer 5

Pathophysiology: arise from melanocytes on epidermal basement membrane or pre-existing nevi
Presentation:
- dark pigmented lesion that can be flat, raised or nodular
- asymmetric, ill-defined borders, multiple colours, diameter >6mm
- ugly duckling rule where melanoma appears abnormal from other nevi
Prognosis: TMN staging
- T: breslow depth is from stratum granulosum to deepest point of invasion. Most important factor where depth >1mm into dermis is poor prognosis
Management:
- excisional biopsy
- surgical removal with possible chemotherapy and radiotherapy

Question 6

Discuss the differences between bullous pemhigoid, dermatitis herpetiform, and pemphigus vulgaris

Answer 6

Antibody:
- IgG
- IgA
- IgG
Site:
- basement membrane
- dermal
- intrapepidermal
Infiltrate:
- eosinophils
- neutrophils
- eosinophils and neutrophils
Management:
- systemic steroids, immunosuppressants, tetracycline 
- gluten-free diet, dapsone
- high dose steroids, immunosuppressants
Association:
- Malignancy
- gluten enteropathy, thyroid disease, intestinal lymphoma
- malignancy with paraneoplastic syndrome

Question 7

Discuss the skin lesions for bullous pemphigoid, dermatitis herpetiform, pemphigus vulgaris

Answer 7

Bullous pemphigoid
- prodrome of urticareal papule and plaque eruption
- pruritic, burning, subepidermal bullae containing serous or hemorrhagic fluid on an erythematous or normal skin base
- heal without scarring
- on flexor surfaces
Dermatitis Herpetiform
- grouped papules/vesicles/urticarial wheals on erythematous base that burn and are pruritic
- extensor surfaces
Pemphigus Vulgaris
- onset of mouth lesion followed by skin lesions in 6-12 months
- flaccid non-pruritic epidermal bullae/vesicles on erythematous or normal skin base
- Nikolsky’s sign
- Asboe-Hansen sign (force applied to bullae they extend laterally)
- on mouth, scalp, face, chest, axillae, groin

Question 8

Discuss the presentation and management of psoriasis vulgaris

Answer 8

Epidemiology: mean age is 33
Presentation:
- well circumscribed erythematous silvery scaled plaques
- can be pruritic leading to erosion and fissure
- Auspitz sign: punctate bleeding spots when psoriatic scales are scraped off
Locations: scalp, extensor elbow, extensor knee, lumbosarcral, umbilical
Severity:
- mild <5% total body surface area
- moderate: 5-10%
- severe: >10%
Management;
- topical treatment for mild: corticosteroid creams for 2-4 weeks
- UVB and topical for moderate: corticosteroid cream in combination with UVB. Can use potent corticosteroid for 2-4 weeks and then intermittently on weekends and vitamin D cream topically every day
- systemic therapy plus topical for severe: UVB and methotrexate is first line, adalimumab is second line

Question 9

Discuss the presentation and management of acne vulgaris

Answer 9

Epidemiology: onset at puberty
Presentation:
- Closed comedome: whitehead
- Open comedome: blackhead
- Inflammatory papule: red, follicular papule
- Inflammatory pustule: red, superficial peri-follicular pustule
- Inflammatory cystic nodule: red, deeper lesion >5mm that leads to scarring
Location: face, neck, upper chest and back
Management:
- topical treatment for mild to moderate papulopustular: salicylic acid, retinoids creams (most effective for comedome but take few weeks to work), benzoyl peroxide creams (antibacterial), topical antibiotics (clindamycin or erythromycin)
- systemic antibiotics for moderate-severe pustular acne, papulopustular acne or cysts: tetracyclines or erythromycin (kill P. Acnes bacteria)
- systemic isoretinoin for severe resistant or nodulocystic acne: accutane (inhibit sebaceous gland activity)
- intralesional steroid injection for nodulocystic acne: decrease inflammation and reduce scarring

Question 10

What are the risk factors for acne vulgaris?

Answer 10

Cosmetics
Chronic rubbing
Stress
Diet high in simple carbohydrates
Medication (corticosteroids, androgen, lithium)

Question 11

Discuss the presentation and management of non-bullous and bullous impetigo

Answer 11

Epidemiology: children 2-6
Organism: Staph aureus in 70% (bullous 100%), group A streptococcus
Presentation:
- Vulgaris: vesicle/pustule that progresses to golden yellow honey-crusted lesion surrounded by erythema
- Bullous: scattered large flaccid superficial clear bullae with yellow or slightly turbid fluid on erythematous or itchy skin (no crust)
Location: face, buttocks, arms, legs
Management:
- self-resolves in 2 weeks
- skin care with wet compresses and Mupirocin for 7-10 days
- widespread can provide Keflex or cloxacillin

Question 12

Discuss the presentation and management of HSV 1&2

Answer 12

HSV1: primary infection causes gingivostomatitis and then reactivation leading to grouped vesicles on erythematous base at mucocutaneous junction
- prodrome of pain, numbness
- location: face, lips
- treatment: antiviral during prodrome
HSV2: multiple vesicles on erythematous base
- incubation of 2-20 days following transmission
- location: genitalia
- investigation: tzanck smear with Giesma stain, definitive through culture of vesicular fluid
- treatment: topical treatment and oral antiviral

Question 13

Discuss the presentation and management of VZV

Answer 13

Primary: incubation of 10-23 days
- vesicle -> pustule -> crust with lesions present in all three stages at same time
- location: face, scalp, trunk, extremeties
- management: symptomatic
Secondary: dormant in dorsal root ganglia
- prodrome of tingling, burning, itching in thoracic dermatome for 0-4 days
- erythematous vesiculopustular rash that may ulcerate and crust in 4-11 days
- post-herpetic neuralgia following treated with pregabalin
- management: topical management, NSAIDs, oral antivirals 72 hours before onset, vaccine