Pigmented lesions

Question 1

Melanocytes are derived from where?

Answer 1

The neural crest

Question 2

Melanoblasta migrate from the neural crest to the…?

Answer 2

Melanoblasts migrate from the neural crest to the skin, uveal tract and leptomeninges

Question 3

What hair colour in eumelanin hair?

Answer 3

Hair colour other than red

Question 4

What does MC1R do to phaeomelanin?

Answer 4

MC1R turns phaeomelanin into eumelanin

Question 5

What happens if you have one defective copy of MC1R?

Answer 5

1 defectiv copy of MC1R causes freckling

2 defective copies cause red hair and freckles

Question 6

Patchy increase in melanin pigmentation
Occurs after UV exposure
Most common in fair skinned and red heads
Reflects clumpy distribution of melanocytes

Answer 6

Freckles (ephilides)

Question 7

Actinic lentigines

• another name?
• related to?
• where do they occur?
• elongated RR?
• increase in which type of cell?

Answer 7

Actinic or solar lentigines (singular lentigo)
Also known as ‘age’ or ‘liver’ spots
Related to UV exposure

Face, forearms and dorsal hands
Epidermis elongated rete ridges
Increase melanin and basal melanocytes

Question 8

Why do you get acquired simple naevi?

Answer 8

During infancy the melanocytes : keratinocyte ratio breaks down at a number of cutaneous sites

This allows formation of simple naevi

Question 9

Neavus development?

Answer 9

Acquired navei develop alon a well-defined pathway:
Junction–>
Compound–>
Intradermal

Question 10

CDKAN2A gene associated with what?

Answer 10

Familial dysplastic naevi and therefore melanoma

Question 11

Life time risk of melanoma in cases of familial dysplastic naevi?

Answer 11

Lifetime risk of melanoma up to 100%

Question 12

Is the epidermis effaced in dysplastic naveii?

Answer 12

No! Unlike melanoma where epidermis is effaced

Question 13

Dysplastic naevi atypia?

Answer 13

Architectural atypia AND cellular atypia

Host reaction-fibrosis and inflammation

Unlike melanoma epidermis not effaced

Question 14

Which type of cells do you get in halo navei?

Answer 14

Halo naevi are overrun by LYMPHOCYTES

Question 15

What type of cells do blue naevi consist of and which layer of the skin are they found in?

Answer 15

Blue navei consist of spindle cells and are ENTIRELY dermal

Question 16

“benign juvenile nevus”?

Answer 16

Spitz nevus

• consist of large spindle and or epithelioid cells
• most are benign but there is a malignant variant

Question 17

Which type of cell are spitz navei composed of?

Answer 17

Consist of large spindle and/or epithelioid cells

Question 18

Four main types of melanoma:

Answer 18

Superficial spreading
Acral/mucosal
Lentigo maligna
Nodular

Question 19

Where would you find superficial spreading melanoma?

Answer 19

Trunk and limbs

Question 20

Where would acral/mucosal melanoma arise?

Answer 20

Acral and mucosal (shocker)

Question 21

Where would lentigo maligna arise?

Answer 21

Sun-damaged face/neck/scalp

Question 22

Where does nodular melanoma arise?

Answer 22

Varied sites, but often trunk

Question 23

RGP and VGP of melanomas?

Answer 23

Rapid growth phase and vertical growth phase

• rapid is when they first grow out the way like macules
• VGP is when they grow downwards and into the DERMIS
• only VGP melanomas can metastasise

(nodular melanoma is a nodule of VGP tumour, no evidence of RGP)

Question 24

What is the breslow depth?

Answer 24

Deppest tumour from granular layer mm

Question 25

Melanoma prognosis largely relates to what?

Answer 25

Melanoma prognosis largely relates to Breslow depth and ulceration

Question 26

What does the suffix “b” mean? e.g. pT3b

Answer 26

Suffix b indicates tumour ulceration e.g. pT3b is a tumour between 2-4mm with ulceration

Question 27

Malignant melanoma treatment?

Answer 27

Primary excision to give clear margins
Some also receive a sentinel node biopsy
If SN positive - regional lymphadenectomy

Treatment of advanced disease difficult
Chemo, immunotherapy, genetic therapies

Question 28

Which type of melanoma may have c-kit mutations and how could you treat them?

Answer 28

Some acral melanoms may have c-kit mutations and may be treated with imatinib

Question 29

Melanomas on intermittently sun-exposed skin may have which type of mutation?

Answer 29

Melanomas on intermittently sun-exposed skin may have a BRAF mutation

Question 30

How can you test for mutations in melanoma?

Answer 30

Can test for mutations on paraffin fixed tissue

Question 31

BRAF

Answer 31

Wild type BRAF is a weak cytosolic proto-oncogene

If mutated drives cell proliferation by up-regulating MEK and ERK

Range of drugs developed to interfere with this pathway e.g. dabrafenib and vemurafenib

Question 32

What are dysplastic naevi?

Answer 32

Generally >6mm diameter
Variegated pigment
Border assymetry