Skin Cancer

Question 1

What are the 2 mechanisms of skin cancer?

Answer 1

• direct action of UV on target cells (keratinocytes) for neoplastic transformation by DNA damage
• effects of UV on the host’s immune system (immune suppression)

Question 2

Describe basal cell carcinoma

Answer 2

• lesion with a shiny shouldered edge, with a degree of ulceration
• mutation of DNA in basal cells results in multiplication and growth of basal cells when they would normally die
• PTCH gene mutation may predispose

Question 3

Describe the treatment of basal cell carcinoma

Answer 3

• surgical excision with 3-4mm margin (gold standard)
• curettage and cautery (scrape away damaged tissue)
• cryotherapy
• photodynamic therapy (immune response induced with UV light to attack cancer cells)
• topical imiquimod/5FU cream
• mohs micrographic surgery (surgery with pathology technician assistance)

Question 4

Describe the different subtypes of basal cell carcinoma

Answer 4

• nodular (most common)
• superficial (red patch, crusting and involvement of blood vessels, flatter)
• pigmented (rolled shiny margin, depressed ulcerated area with dark brown pigmentation)
• morphoeic/sclerotic (subtle area of skin colour change, shiny, what you see is not representative of true margins)

Question 5

Describe the features of squamous cell carcinoma

Answer 5

• may occur in normal skin, injured skin, or chronically inflamed skin
• originates in keratinocytes
• pre-malignant variants (actinic keratoses, Bowen’s disease)
• most occur on skin regularly exposed to sunlight/UV radiation
• appears as keratin crust and scaling, inflammation + areas of pigmentation

Question 6

What is the treatment for squamous cell carcinoma?

Answer 6

• surgical excision with 4mm margin (high rate of relapse so increased margin) = gold standard
• curettage and cautery (in certain scenarios)
• premalignant syndrome = topical imiquimod/5FU cream, cryotherapy, photodynamic therapy, sun protection

Question 7

Describe the features of melanoma

Answer 7

• tumour of melanocytes
• most common in skin (but can occur in bowel/eye)
• DNA damage (mainly UV, rarely genetic)
• has radial growth phase, then deeper vertical growth
• can spread by lymphatic system
• has a premalignant form

Question 8

What are the risk factors of melanoma?

Answer 8

• genetic markers
• family history
• UV radiation
• sunburns during childhood
• melanocytic/congenital/atypical nevi
• personal history of melanoma
• very fair skin
• DNA repair defects eg. Xeroderma pigmentosum
• immunosuppression

Question 9

Describe the subtypes of melanoma

Answer 9

• superficial seeding
• nodular
• acral (affecting digits and toes)
• subungual (under nail)
• amelanotic (red rather than pigmented)
• lentigo meligna (pre-malignant precursor in sundamaged skin of face and neck)
• lentigo meligna melanoma
• melanoma in situ (precursor for melanoma in other areas)

Question 10

What is the treatment of melanoma?

Answer 10

• surgical excision (breslow <1mm = 1cm margin, >1mm = 2cm margin)
• immunotherapy (ipilimumab, nivolumab)
• immune checpoint/MEK inhibitor (trametinib)
• biologic antibodies for genetic defects (eg. BRAF defects)
• imaging/scanning CT/MRI/PET
• long term follow up, assessment of lymph nodes/organ spread, genetic testing in family with multiple primary melanomas

Question 11

Describe different cutaneous tumour syndromes

Answer 11

• Gorlin’s syndrome (multiple BCCs, jaw cysts, risk of breast cancer)
• Brooke Spiegler syndrome (multiple BCCs, trichepitheliomas)
• Gardner syndrome (soft tissue tumours, polyps, bowel cancer)
• Cowden’s syndrome (multiple hamartomas, thyroid, breast cancer)