Melanoma

Question 1

What is melanoma?

Answer 1

Proliferation of atypical melanocytes with potential for dermal invasion and widespread metastasis.

• sun is a risk factor but not as important as in SCC or BCC
• 70% from normal skin, 30% from pre-existing naevi
• women on lower legs and present sooner
• men on back

Question 2

Risk factors for melanoma?

Answer 2

• sun is a risk factor but not as important as in SCC or BCC

Risks:

• male gender
• FHx melanoma 2x risk
• white vs black 19x risk
• age 10x risk in 70yo vs 30yo
• multiple naevi (moles) >100 is 7x more risk than <15 (more than 50 is significant)
• previous sunburn 2x risk
• previous skin cancers
• smoking
• sunburn before age 10

Question 3

Pathology of melanoma?

Answer 3

• melanocytes come form neural crest cells
• normal lifecycle is to skrink and lose melanin abilities before dying
• mutation in cell to proliferate
• average caucasian has 30 moles
• only 1 or 2 at birth
• acquire moles during teenage years
• new moles after 40 is worrying
• moles naturally become larger and darker during pregnancy

Question 4

Types of melanoma

Answer 4

LENTIGO MALIGNA MELANOMA

• 15% of cases
• usually on face or sun exposed areas on elderly
• typically large, flat, dark lesion

SUPERFICIAL SPREADING MELANOMA

• 65% of melanoma
• legs of women and torso / back of men
• slightly raised plaque

NODULAR MELANOMA

• 10-15% cases
• anywhere on body
• occasionally pearly or lack pigment
• rarely metastasise but grow rapidly

ACRAL AND SUBUNGAL MELANOMA

• relatively rare, most common melanoma in black africans
• usually seen on palms or soles or subungal skin (under fingernails)

Question 5

Where does melanoma spread?

Answer 5

• local lymph nodes
• satellite lesions (nearby nodules or papules, may not be pigmented)
• skin
• rarely to internal organs

Question 6

Treatment of melanoma?

Answer 6

Excision is the only treatment.
- margin is guided by the BRESLOW DEPTH

1mm thick = 1cm margin
1-2mm = 1-2cm margin
2-4mm thick = 2-3cm
>4mm thick = 3cm margin

• examine lymph nodes, biopsy recommended if depth >1mm

Question 7

Prognosis of melanoma?

Answer 7

Correlates to depth of dermal spread:
BRESLOW DEPTH

<0.76mm = >98% survival

> 3mm = 45% survival

After metastasis, 5yr survival is about 10%

(Breslow is measured from stratum granulosum down to lowest abnormal cell)

Question 8

Follow up in melanoma?

Answer 8

BRESLOW DEPTH

<1mm thick = 6 monthly for 2 years

1-2mm thick = 4 monthly for 2 years, 6 monthly for 2 years, yearly for 10 years

> 2mm thick = annual CXR and regular GP and specialist follow up