Skin Cancer Overview and Epidemiology

Question 1

Types of skin cancer?

Answer 1

Malignant melanoma (most serious form of skin cancer)

Non-melanoma skin cancer:
Basal cell carcinoma (BCC)
Squamous cell carcinoma (SCC)

Question 2

How do non-melanoma skin cancers arise?

Answer 2

From keratinocytes within the epidermis:

BCC arises from keratinocytes within the basal layer of the epidermis

SCC arise from supra-basal layers

Question 3

How do malignant melanomas arise?

Answer 3

Arise from the melanocytes (pigment-forming cells) which are found scattered along the basal layer of the epidermis

Question 4

Why is the incidence of skin cancer increasing?

Answer 4

Demographic and behavioural factors:

Ageing populations

UV exposure incidence increasing, inc. younger people

Question 5

What % of skin cancers are malignant melanomas?

Answer 5

Only 5% of all skin cancers but 75% of deaths

Question 6

What does melanoma survival depend upon?

Answer 6

Tumour depth:

Breslow thickness 4 mm confers a 50% melanoma survival

Metastases confers a 5% melanoma survival

Question 7

Identification of a malignant melanoma?

Answer 7

A - asymmetry
B - border
C - colour
D - diameter
E - evolution

Question 8

What is the “ugly duckling” sign?

Answer 8

Observation that naevi in the same individual tend to resemble one another, and that MM often deviates from this naevus pattern

Question 9

Dermascopy of a malignant melanoma reveals?

Answer 9

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

Question 10

How common are BCCs?

Answer 10

Very common; comprise 75% of all non-melanoma skin cancers

Question 11

Clinical presentation of BCC?

Answer 11

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

Question 12

Different names and types of BCC?

Answer 12

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

Question 13

Spread of BCC?

Answer 13

LOCALLY INVASIVE. but rarely metastasise

Question 14

Clinical presentation of SCC?

Answer 14

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

Question 15

Differentiation of SCCs?

Answer 15

Majority are well-differentiated, low-risk SCC

Minority are poorly differentiated, high-risk SCC

Question 16

Prognosis of SCC?

Answer 16

5% risk of metastases but, once this happens, the prognosis is poor

Question 17

Pre-cursor lesions of SCC?

Answer 17

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

Question 18

What is keratoacanthoma?

Answer 18

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

Question 19

What are cutaneous horns?

Answer 19

Hard conical projections from the skin, made of compact keratin; arise from benign, pre-malignant or malignant skin lesions

More common in elderly

Question 20

High risk sites for SCC?

Answer 20

Ears, lips, scalp

Question 21

Risk factors for skin cancer?

Answer 21

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)

Question 22

Genetic risk factors for skin cancers?

Answer 22

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)

Question 23

Major features of Gorlin’s syndrome?

Answer 23

Multiple, early-onset BCCs

Palmar pits (on hands)

Jaw cysts

Ectopic calcification of the falx cerebri

Question 24

Minor features of Gorlin’s syndrome?

Answer 24

Skeletal abnormality

Macrocephaly, OFC > 97th centile (larger head circumference)

Cardiac/ovarian fibroma

Medullablastoma

Question 25

Prevention of skin cancer?

Answer 25

1. Behaviour:
Avoid sun at peak times
Utilise shade
Part. care of babies/children
Avoid sunbeds

2. Clothing:
   Tightly woven, loose-fitting clothing (dark)
   Long sleeves, trousers, skirts

3. Sunscreens:
Broad spectrum (SPF25 +) with UVA protection

4. Regular self-surveillance