Melanoma

Question 1

Define in-transit metastasis

Answer 1

intralymphatic metastasis >2cm from primary site but not beyond the nearest regional lymph node basin

Question 2

5y survival vs mitotic rate (mm2) in melanoma

Answer 2

0: 98%
1: 98%
2-3: 96:
4-10: 91%
>11: 84%

Question 3

Margins and T stage for excision of melanoma

Answer 3

<1mm: 10mm (T1)
1-2mm: 10-20mm (T2)
2-4mm: 20mm (T3)
>4mm: 20mm (T4)

Question 4

Would you recommend a SLNB for melanom 0.8-1mm?

Answer 4

Depends on clinical context and other high-risk factors of the melanoma
Microsatellitosis or in-transit metastasis upgrades to N2c disease so SLNB recommended

Question 5

Risk factors for melanoma

Answer 5

Sun exposure history
Family history
Complexion
Immunosuppression
Age
Dysplastic naevus syndrome
Previous non-melanoma skin cancers

Question 6

Who would you offer a PET CT to?

Answer 6

Stage II disease: conflicting evidence - low yield and high false positive rate, however if true metastasis detected the clinical management and prognosis will significantly change
Stage III disease: yes before considering surgery, particularly lymphadenectomy, as may upstage the disease
Stage IV disease: yes following discussion in melanoma MDM - oligometastases that may be amenable to surgery, or equivocal findings on standard CT

Question 7

What are the principles of an initial excision of a suspicious pigmented lesion

Answer 7

A narrow complete excision biopsy with 2mm margins, ensuring the base is not transected, and with planning for definitive wide excision in mind, ie avoiding lymphatics

Question 8

Who would you offer adjuvant radiotherapy to following CLND for melanoma? (4)

Answer 8

> 3 nodes
node >3cm
extracapsular extension of clinically palpable disease
regionally recurrent disease

Understanding that the lymphoedema risk increases markedly

Question 9

What local therapies are available for in-transit disease?

Answer 9

Treatment in the context of a clinical trial

IL-2 intralesional injection
Isolated limb infusion/perfusion
Radiotherapy
Laser ablation
Topical imiquimod

Question 10

What is dysplastic naevus syndrome?

Answer 10

Used to be familial atypical multiple more and melanoma syndrome
AD mutation in CDKN2A

Question 11

What naevi do melanoma develop from?

Answer 11

Large congenital naevi: 5-8% lifetime risk
Benign naevi if >200, or >20 on arms
Dysplastic naevi: different colour, irregular border
- monitor

Question 12

What is lentigo maligna?

Answer 12

Lentigo maligna: melanoma in situ
Grows over years
Face, neck, hands
Often pigmented, asymmetric
Histo: malignant melanocytes propagating along base of epidermis and extending up into corneal layer

Can progress to lentigo maligna melanoma after years

Question 13

What features of the histology report are important in melanoma? (7)

Answer 13

Breslow thickness (in mm)
Ulceration
Mitoses/hpf
Microsatellitosis
LVI/PNI
Tumour infiltrating lymphocytes
Level of dermal invasion (Clark level) - gives idea of risk of metastasis if IV/V

Question 14

Superficial spreading melanoma: characteristics

Answer 14

Most common type of melanoma: 60%
Lower limb (women)
Back (men)
High intensity intermittent sun exposure
Asymmetric, irregular borders, different colours
Radial growth phase then invasive

Question 15

Acral lentiginous melanoma: characteristics

Answer 15

5% melanoma
Sole of foot, palm of hand
Dark skinned people
Radial growth phase then invasive
C-KIT mutation common

Question 16

Desmoplastic melanoma: characteristics

Answer 16

1-4% melanoma
Sun-damaged skin of head and neck
Older patients
50% amelanotic
Flat nodule, like thickened plaque

Histo: spindle celled melanocytes with fibrous stroma
Can be mixed with other melanoma (poor survival) or pure
20% local recurrence so needs wider margins

Double response to PD1 therapy due to higher tumour mutation burden

Question 17

Nodular melanoma: characteristic

Answer 17

15% melanoma
More common in men
Amelanotic
Rapidly growing
Elevated, evolving lesion (looks like a BCC or SCC sometimes)
Aggressive

Question 18

Lentigo maligna melanoma: characteristics

Answer 18

10-15% melanoma
Arises in precursor of lentigo maligna
Watch for change in pigmented lesion with nodule
Face, neck, hands of elderly people
High rate of recurrence 15-20%

Question 19

Malignant changes of melanoma

Answer 19

Radial growth: atypical melanocytes dependent on growth factors from surrounding keratinocytes
Invasive phase: invade epidermis and penetrates dermis and sc tissues: now have own growth factors and are highly metastatic

S100, melan-A, SOX-10, HNB-45

BRAF mutations common, esp in chronic sun damaged skin
- targeted therapy available

CDKN2A mutation (dysplastic naevus syndrome, familial)

Question 20

Indications for isolated limb infusion or perfusion for melanoma

Answer 20

Locally advanced tumour
Unresectable without mutation
Very large tumour
Mult satellite/in-transit mets
Invasion into adj structures

Remember ILP needs exposure of femoral vessels and ECMO
ILI is percutaneous access and a coil

Question 21

What to do with melanoma lymphadenopathy and unknown primary?

Answer 21

Stage: CT PET, CT/MRI brain
Lymphadenectomy
Adjuvant therapy

Question 22

Why do an SNB in melanoma?

Answer 22

Decrease the number of non-therapeutic lymphadenectomies
Identify those who may benefit from adjuvant treatment
Increase the accuracy of staging

Question 23

Who is offered a lymphadenectomy in melanoma?

Answer 23

Clinically or radiologically positive lymph nodes
Metastatic disease where local control is desired (toilet lymphadenectomy)
Lymphadenopathy with unknown primary

High risk positive SNB
- tumour rupture
- extracapsular extension
- multiple nodes
- immunosuppressed patient

Question 24

What is Cloquet’s node?

Answer 24

The lymphatic tissue medial to the femoral vein in the superior aspect of the femoral canal

Thought to represent the draining node into pelvis from lower limb (junction between deep inguinal nodes and external iliac nodes)