Skin Cancer

Introduction

• Skin cancer is the most common malignancy – and the incidence is increasing rapidly
• In the last 10 years, the incidence in the UK has doubled
• Mainly seen on sun damaged / sun exposed areas of skin
  • Face / head, neck, forearms, upper chest
• 95% of skin cancers are SCC or BCC
  • BCC – approx 65% – with a 0.1% mortality
  • SCC – approx 30% – with a 5% mortality
  • <5% are melanoma – with a 10% mortality
• Skin cancers are responsible for 2% of cancer deaths each year in the UK
• 80% of skin cancer deaths are due to melanoma
• The treatment of SCC and BCC is very similar
• Melanoma requires a more definitive option
• Biopsy is generally a good idea for skin lesions if you are not sure of the origin – EXCEPT for pigmented lesions. Melanoma can be missed during a biopsy. A negative biopsy of a pigmented skin lesion does not rule out a melanoma. Surgical excision is the only suitable treatment option for suspected melanoma.
• Consider doing a full skin check  in anyone with a suspicious lesion
• Be aware of new or changing lesion in mature adults

General Risk Factors

• Age
• Sun bed use
• Fair skin
• Hx of sunburn
• Hx of living overseas / or in places with a lot of sun exposure (e.g. Australia!)
• FH
• Occupations – outdoors – e.g. bricklayers, keen gardeners or cyclists
• Phototherapy

Assessing Skin Lesions

ABCDE

Use this method to approach the assessment of any skin lesion

• A – Asymmetry – break it into 2 axes
  • Look for different matrices
• B – Border (irregularity)
• C – Colour – multiple different colours is bad!
• D – Diameter – >7mm
• E – Evolution / enlargement

7 point checklist for melanoma

A modified version is often used, particularly when assessing pigmented lesions for risk of melanoma. This is know as the “7-point checklist”. A score of three indicates the need for excision:

1. Size >7mm
2. Recent change in size of lesion
3. Irregular border
4. Irregular pigmentation
5. Itch or irritation
6. Inflammation
7. Oozing or crust of the lesion

Also look out for:

• Assymetry
• “Ugly Duckling” – the lesion that really stands out compared to other lesions

The three point check-list

A simplified scale for assessing the risk of a pigmented skin lesion for melanoma

• Asymmetry – colour and structure
• Atypical Network – more than 1 type of ‘network’
• Blue / white structures – white scar-like areas, blue/grey areas, structureless areas

An abnormality in any of these areas is worth one point

• 0 or 1 –  likely benign
• 2 or more – needs excision / removal – high risk for melanoma

Example

Here is a melanoma. Note its asymmetry when split into 4 quadrants. Note that there are different types of pigmentation (different ‘networks’). There is not any obvious scarring nor blue-white structures. The border is very irregular. It is likely to be larger than 7mm. There is no inflammation, and no oozing or crust.

• On the 7 point checklist – this scores a 3 on appearance along, and maybe a 5 if recent change in size or itch – LIKELY MELANOMA
• On the 3 point checklist – this lesions scores a 2 – LIKELY MELANOMA

Squamous Cell Carcinoma

Risk Factors

• Smoking
• Sun Exposure
• Presence of premalignant lesions (actinic keratosis)
• Age
• Skin trauma
• Exposure to carbon containing compounds
• Asbestos
• Arsenic
• Ionizing radiation
• Metals
• Non-solar UV radiation – e.g. welders
• 3x more common in men
• Occupational – e.g. builder / farmer – associated with chronic low-grade sun exposure

Presentation

• Solitary papule / nodule, often eroded at the centre, or crusty, purulent or bleeding
• Usually a ‘fleshy’ lesion
• May resemble giant warts, but, unlike warts, may be painful
• Usually in a sun-exposed area
• Often hard, scaly, dome-like structures
• Can bleed or itch
• Also related to smoking, and may be present on the lower lip
• Bowen’s disease = SCC in situ (hasn’t yet spread)

Treatment

• The definitive treatment is surgical excision with minimum 2mm margin
  • Excision with wide surgical margins
  • Small tumour – 2-4mm margin
  • Normal margin – 5mm – success rate – 95%
  • High risk tumour site – not exposed to sun, lips, anus. These need larger excision to reduce the risk of metastasis (10mm margin)
• Many can be treated with topical cream
  • 5-fluorouracil is the recommended treatment – applied 1-2x daily for 4 weeks (max 12 weeks)
  • Immiquimod – applied once daily, 5x a week fo rum to 6 weeks is an alternative
  • Can cause scarring
  • You don’t get a histological diagnosis
  • You can never be sure if it has been completely fully treated
• May also be treated with cryotherapy (liquid nitrogen). Similar risks to topical cream treatments – particularly can cause scarring especially if used on the face – be careful!
• Metastases – rare
  • Lymph nodes
• Solar keratoses
  • These are superficial precursors to SCC
  • Often in sun exposed areas
  • Can be treated with topical agents or cryotherapy
  • Often only require a short burst of cryotherapy – 1-2 cycles of 8-10 seconds each

 Examples

Melanoma

• Proliferation of atypical melanocytes with potential for dermal invasion and widespread metastases
• Sun exposure still a risk factor, but not as important as SCC or BCC. Other risk factors include:
  • Male Gender
  • >50 “moles” (benign naevi)
  • FHx of melanoma
  • Fair complexion
  • Smoking
• 70% arise from normal skin, 30% arise from pre-existing naevi
• Women – Common on lower legs. Women tend to present sooner for many reasons – they tend to be better at checking their skin, and more concerned about skin lesions.
• Men – Common on back

Epidemiology

• Most dangerous type of skin cancer – highest mortality of the three main types of skin cancer
• Most likely to metastasize
• Men – about 1/14 lifetime risk (in Australia)
• Women – about 1/24 lifetime risk (in Australia)
• Only account for about 3% of skin cancers
• 4^th most common type of cancer in Australia
• Australia has the highest incidence of melanoma in the world
• Incidence 52 per 100 000 in Australia

Risk Factors

• Family history of melanoma – doubles your risk
• Skin Type – White skin vs black skin – 19x risk
• Age – 70yo men 10x risk of 30yo men
• PMHx melanoma – 10x risk
  • Recurrence most likely to occur in the first 5 years
• Multiple Naevi (‘moles’) – >100 – 7x risk (compared to someone with <15 moles)
  • >50 naevi is significant
• Sun – UVB is the main type of UV ray causing melanoma risk – compared to UVA which is more likely to cause BCC or SCC
• Previous Sun burn – 2x risk
• Previous other skin cancers (BCC or SCC) then 4x the risk of background
• Giant congenital naevus >20cm
• Red hair freckles skin types
• Sun exposure – particularly sunburn before the age of 10

Pathology

• Melanocytes derived from neural crest cell.
• The normal life cycle of a melanocyte is to gradually shrink in size and lose melanin producing abilities before they die
• If there is a mutation then the cell can start to proliferate and divide and grow in size
• 50-70% arise de novo. The rest present at the site of existing ‘moles’
• The average Caucasian has 30 moles
  • You are born with only 1-2
  • Most are acquired in teenage years
  • New moles after the age of 40 are worrying!
• Caution during pregnancy!
  • Malignant melanoma is no more common during pregnancy
  • Moles can change size and become darker during pregnancy
• Rare sites for lesions include mucosa (particularly in the anal region), genital regions and conjunctiva

Types of melanoma

• 15% of cases of melanoma
• Usually on the face (or other sun exposed areas) in elderly patients
• Typically a large, flat, dark lesion

Superficial spreading melanoma

• About 65% of melanomas
• Most commonly on the legs of women, and the torso/back of men
• Appears like a slightly raised plaque

Nodular Melanoma

• 10-15% of cases
• Anywhere on the body
• Often dark coloured
• Occasionally may be pearly or lack pigment
• Very rarely metastasise, but grow rapidly

Acral and subungal melanoma

• Relatively rare, but the most common melanoma in Black Africans
• Usually seen on the palms or soles, or subungal skin (under fingernails)

Spread

• Local lymph nodes
• Satellite lesions – usually nearby, nodules or papules that may or may not be pigmented
• Skin
• Internal organs  – rare

Treatment

• Excision is the only treatment
• Margins are guided by the extent of spread (depth) on histology. Usually a 2mm margin is taken at the original excision, and sent for histology. Then, when results are available, re-excise the site with the following suggested margins:
  • Melanoma in situ – 5-10mm margin
  • Melanoma <1mm thick – 10mm margin
  • 1-4mm thickness – 10-20mm margin
  • >4mm thickness – 20mm margin
  • This thickness is referred to as the Breslow depth
• Margins laterally and should be removed down to the fascia (including all subcutaneous fat)
• Examine lymph nodes and for organomegaly
• >4mm depth of tumour has >60% chance metastasis
• Do NOT biopsy pigmented skin lesions – the melanoma itself can be missed in an area of naevus – not good for patient (or later on for doctor!)
• Biopsy of local lymph nodes recommended for melanoma of depth >1mm

Prognosis

• This is correlated to the depth of dermal spread, and to the histological appearance. The Breslow depth is a scale often used as a prognostic indicator:

Follow Up

• <1mm thickness – 6 monthly for 2 years
• 1-2mm thickness – 4 monthly for 2 years, 6 monthly for 2 years, yearly for 10 years
• >2mm thickness – annual CXR and regular GP and specialist FU

Basal Cell Carcinoma – BCC – aka Rodent Ulcer

Risk factors

• Fair skin
• Sun exposure – accumulative lifetime exposure

Presentation

• Usually nodular
• May be erythematous, or non-pigmented
• May be plaque-like
• May be ulcerated
• They can sometimes crust over, and apparently undergo some healing and reduction in size, but generally, enlargement is slowly progressive.

Treatment

• Surgical excision is treatment of choice
  • 3mm margin usually adequate
• Can also be treated topically
  • 1st is Imiquimod – applied once daily, 5 days a week for up to 6 weeks
  • Do NOT treat topically if on head or neck – these need surgical excision
  • Cryotherapy may also be suitable for smaller, superficial well defined lesions

Like with SCC:

• Topical agents
  • Can cause scarring
  • You don’t get a histological diagnosis
  • You can never be sure if it has been completely fully treated

Examples

Other Types of Skin Lesion

Seborrhoeic Keratoses

• Crusty
• Often luck like they are ‘stuck on’
• Like barnacles!
• Are benign and can be left alone. Patient may decide they don’t like the appearance, or it may catch on clothing, or it may be itchy or irritating – all of which are reasonable indications for removal
• Can shave off. Can use curettage (burn off)
• Can cut off / frozen off
• Not usually treated with topical agents
• May be mistaken for melanoma as they are often pigmented

Examples

Campbell de Morgan Spots

• Red spots that occurr over body with age
• Benign
• Sometimes raised
• Sometimes Flat

Solar Keratoses (aka actinic keratosis)

• Sun damaged
• Pre cancerous – can turn into SCC
• Often red and scaly
• Can treat with cryotherapy or Effudix (5-fluorouracil)

Dermatofibroma

• Central scare like area with peripheral light brown network
• Benign

Congenital naevus

• “Cobblestone” pattern
• Usually develop early in life

Reticular Naevi

• Benign
• What a lay person would most likely call a ‘mole’

Blue Naevi

• Homogenous blue coloration. Often very Dark coloured
• Usually very symmetrical and very well defined borders
• Usually solid block of colour

Three types of pattern

• Reticular Pattern
• Cobblestone pattern
• Homogenous blue
• Is it symmetrical pattern and homogenous colour?

Special Naevi

• Acral Naevus – often on the fingers. Wither dermatoscope often has well defined ‘furrows’ and ‘ridges’

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