Skin Cancer Overview and Epidemiology Flashcards
Types of skin cancer?
Malignant melanoma (most serious form of skin cancer)
Non-melanoma skin cancer:
Basal cell carcinoma (BCC)
Squamous cell carcinoma (SCC)
How do non-melanoma skin cancers arise?
From keratinocytes within the epidermis:
BCC arises from keratinocytes within the basal layer of the epidermis
SCC arise from supra-basal layers
How do malignant melanomas arise?
Arise from the melanocytes (pigment-forming cells) which are found scattered along the basal layer of the epidermis
Why is the incidence of skin cancer increasing?
Demographic and behavioural factors:
Ageing populations
UV exposure incidence increasing, inc. younger people
What % of skin cancers are malignant melanomas?
Only 5% of all skin cancers but 75% of deaths
What does melanoma survival depend upon?
Tumour depth:
Breslow thickness 4 mm confers a 50% melanoma survival
Metastases confers a 5% melanoma survival
Identification of a malignant melanoma?
A - asymmetry B - border C - colour D - diameter E - evolution
What is the “ugly duckling” sign?
Observation that naevi in the same individual tend to resemble one another, and that MM often deviates from this naevus pattern
Dermascopy of a malignant melanoma reveals?
Blue-white veil -irregular structureless area of confluent blue pigment with a ground glass haze, as if the image were out of focus
It is due to hyperkeratinisation over dense epidermal pigment
How common are BCCs?
Very common; comprise 75% of all non-melanoma skin cancers
Clinical presentation of BCC?
Slow-growing lump or non-healing ulcer; this is due to tumour : blood supply mismatch leading to cell death and central ulceration
PAINLESS and thus easily ignored
“Pearly” or translucent with visible, arborising blood vessels
Different names and types of BCC?
With a central ulceration - “rodent” ulcer
Scaly plaque - “superficial”
Infiltrative - “morphoeic”
Slightly scaly, irregular plaque with a thin, translucent rolled border and multiple microerosions - superficial
With dark/black coloured patches - pigmented BCC
Nodulocystic BCC presents as a solitary, shiny, red nodule with large telangiectatic vessels, often seen on the face - nodulocystic BCC
Spread of BCC?
LOCALLY INVASIVE. but rarely metastasise
Clinical presentation of SCC?
Presents in a no. of ways, e.g:
Hyperkeratotis (crusted) lumps lump/ulcer
May arise on sun-damaged skin and grow relatively FAST
May be painful and/or bleed
Differentiation of SCCs?
Majority are well-differentiated, low-risk SCC
Minority are poorly differentiated, high-risk SCC
Prognosis of SCC?
5% risk of metastases but, once this happens, the prognosis is poor
Pre-cursor lesions of SCC?
Actinic keratoses - scaly spot found on sun-damaged skin; it is a pre-cursor or early form of cutaneous SCC; assoc. with a high risk of developing SCC or BCC
Bowen’s disease (carcinoma-in-situ) - AKA intra-epidermal carcinoma; an early stage of SCC
What is keratoacanthoma?
Skin lesion that erupts in sun damaged skin; grows for a few months, then may shrink and resolve by itself
Considered to be a variant of the SCC
What are cutaneous horns?
Hard conical projections from the skin, made of compact keratin; arise from benign, pre-malignant or malignant skin lesions
More common in elderly
High risk sites for SCC?
Ears, lips, scalp
Risk factors for skin cancer?
Sun exposure
Genetic predisposition
Immunosuppression
HPV infection
Transplant recipients
Other environmental carcinogens, e.g: coal tar, smoking, ionising radiation, arsenic, trauma, chronic ulceration (e.g: on the leg; they may become malignant)
Genetic risk factors for skin cancers?
DNA repair syndromes, e.g: Xeroderma pigmentosum (defect in 1 of 7 nucleotide excision repair genes) causes photosensitivity, skin cancer on UV exposed sites, neurological deterioration and increased risk of other cancers
Albinism - no melanin/UV protection
Naevoid BCC (Gorlin’s syndrome) - autosomal dominant condition characterised by multiple and early onset BCCs, as well as other cancers
Dystrophic epidermolysis bullosa - autosomal recessive and increases the risk of SCC
Hereditary Type VII collagen deficiency (RDEB)
Major features of Gorlin’s syndrome?
Multiple, early-onset BCCs
Palmar pits (on hands)
Jaw cysts
Ectopic calcification of the falx cerebri
Minor features of Gorlin’s syndrome?
Skeletal abnormality
Macrocephaly, OFC > 97th centile (larger head circumference)
Cardiac/ovarian fibroma
Medullablastoma
Prevention of skin cancer?
1. Behaviour: Avoid sun at peak times Utilise shade Part. care of babies/children Avoid sunbeds
- Clothing:
Tightly woven, loose-fitting clothing (dark)
Long sleeves, trousers, skirts
3. Sunscreens: Broad spectrum (SPF25 +) with UVA protection
- Regular self-surveillance
