Skin Cancer

Original article by Tom Leach | Last updated on 7/6/2014
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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
  • Responsible for 2% of cancer deaths each year
  • 80% of these are melanoma
 

General Risk Factors

  • Age
  • Sun bed use
  • Fair skin
  • Hx of sunburn
  • Hx of living overseas
  • FH
  • Occupations – outdoors – e.g. bricklayer
  • Phototherapy
 

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
  • Also related to smoking, and may be present on the lower lip
  • Bowen's disease = SCC in situ (hasn't yet spread)
 

Treatment

  • Excision with wide surgical margins
  • Small tumour – 4mm margin
  • Normal margin – 6mm – 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)
    • Metastases - rare
    • Lymph nodes
 

Malignant melanoma

  • Proliferation of atypical melanocytes with potential for dermal invasion and widespread metastases
  • Sun exposure still a RF, but not as important as SCC or BCC
  • Women - Common on lower legs. Women present sooner – as they are better at checking their bodies!
  • Men - Common on back
 

Pathology

  • 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
 

Risk factors

  • Giant congenital naevus >20cm
  • FH
  • MOLES! >50 moles >2mm size
  • Red hair freckles skin types
  • Sun exposure – particularly sunburn before the age of 10
 

The lesion

ABCDE
  • A – asymmetry
  • B – border is irregular
  • C – colour – lesion of >1 colour
  • D – diameter > 7mm
  • E – enlarging/evolving
 

Types of melanoma

Lentigo maligna 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
  • 2-5mm margins
  • Examine lymph nodes and for organomegaly
  • >4mm depth of tumour has >60% chance mets

Prognosis

  • This is correlated to the depth of dermal spread, and to the histological appearance. The Breslow thickness is a scale often used as a prognostic indicator:
Tumour Thickness (mm)
5-Year Survival
<0.76
>98%
0.76 – 1.5
90%
1.51 – 2.25
83%
2.26 – 3.0
75%
>3
45%
After metastasis, 5yr survival is about 10%
  

Basal Cell Carcinoma – BCC – aka Rodent Ulcer

Basal cell carcinomas are the most common form of skin cancer, but metastasis is rare, and they are slow growing. They can be very destructive locally, and arise from epidermal basal cells.
 

Risk factors

  • Fair skin
  • Sun exposure – accumulative lifetime exposure
 

Presentation

Typically – a pearly nodule with a raised, red, edge. May be scaly. Often on the face.
Can be highly variable
  • 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

  • Remove the lesion!
  • This can be in the form of curette, surgical excision, or cryosurgery.
 
Recurrence rate is about 5%