DERM: Melanocytic Naevi and Malignant Melanoma

Question 1

what is a melanocytic naevus?

Answer 1

also known as a mole, a common benign skin lesion caused by a proliferation of melanocytes (naevus cells), can be congenital or acquired.

A benign collection of pigment-producing cells (melanocytes) in the epidermis, dermis, or both.

plural = naevi

Question 2

what are some clinical features of melanocytic naevus?

Answer 2

(mole)

• Can be anywhere on the body
• More common in fair skinned people
• Usually asymptomatic
• Flat or raised
• Vary in colour, size and shape

Question 3

what is a junctional naevus?

Answer 3

(mole)

between the epidermis and the dermis, flat, usually mid to dark brown.

Question 4

what is a compound naevus?

Answer 4

(mole)

within the dermis and at the epidermal-dermal junction, raised centre with a flat surrounding area, often hairy.

Question 5

what is a intradermal naevus?

Answer 5

(mole)

within the dermis, raised, often hairy, paler.

Question 6

True of false… People with lots of moles have an increased melanoma risk?

Answer 6

True

People with lots (>100) of moles have an increased melanoma risk (risk increases as number of moles increases)

Question 7

what is the treatment for a melanocytic naevus?

Answer 7

• usually none

- may be surgically removed

Question 8

why might a melanocytic naevus be surgically removed?

Answer 8

If there is uncertainty as to whether it is benign or malignant

If the mole causes problems e.g. catches on clothing

For cosmetic reasons

Question 9

what is a malignant melanoma?

Answer 9

skin cancer of the melanocytes

Occurs due to uncontrolled melanocyte proliferation

Question 10

what is an in situ melanoma?

Answer 10

skin cancer of the melanocytes - epidermis only

Question 11

what is an invasive melanoma?

Answer 11

skin cancer of the melanocytes - spread to the dermis

Question 12

what is an metastatic melanoma?

Answer 12

skin cancer of the melanocytes - spread elsewhere than the epidermis/dermis

Question 13

what are some risk factors for a malignant melanoma?

Answer 13

• high UV exposure (especially during childhood)
• Skin type 1 (never burns, never tans)
• increasing age
• history of skin cancer
• having a lot of melanocytic naevi
• Having >5 atypical naevi
• Family history of melanoma
• Genetics (BRAF mutation)

Question 14

what are some clinical features of a malignant melanoma?

Answer 14

• Anywhere on the body Common sites = back (men), legs (women)
• May be itchy, painful, bleed, have an overlying crust

Question 15

what is a Amelanotic melanoma?

Answer 15

Amelanotic melanoma: melanoma with no pigment

Question 16

when examining a mole, what approach do you take?

Answer 16

ABCDE + Symptoms

Asymmetry
Borders (irregular)
Colour (irregular, variation)
Diameter (>6mm)
Evolving (changing in size/shape/colour)

Symptoms (bleeding, itching, pain etc)

Question 17

what is the treatment for a malignant melanoma?

Answer 17

surgery (wide local excision):

• suspected melanomas are always excised, sampling is inappropriate
• Removal of affected lymph nodes (if melanoma has spread)
• Radiotherapy (in some cases)

NB: chemotherapy for metastatic melanomas

Question 18

In situ melanomas are cured with excision, however, invasive melanomas may metastasise or recur, what is the risk of recurrence/metastasis based on?

Answer 18

Breslow thickness

<1mm thick = low risk
1-4mm thick = intermediate risk
>4mm thick = high risk

NB: Risk of metastasis can also be assessed with Clark level (the higher the level, the greater the risk of metastasis)…

Level 1 = in situ melanoma
Level 2 = invasion of papillary dermis
Level 3 = complete invasion of the papillary dermis
Level 4 = invasion of reticular dermis
Level 5 = invasion of subcutaneous tissue