Pigmented lesions Flashcards
Melanocytes are derived from where?
The neural crest
Melanoblasta migrate from the neural crest to the…?
Melanoblasts migrate from the neural crest to the skin, uveal tract and leptomeninges
What hair colour in eumelanin hair?
Hair colour other than red
What does MC1R do to phaeomelanin?
MC1R turns phaeomelanin into eumelanin
What happens if you have one defective copy of MC1R?
1 defectiv copy of MC1R causes freckling
2 defective copies cause red hair and freckles
Patchy increase in melanin pigmentation
Occurs after UV exposure
Most common in fair skinned and red heads
Reflects clumpy distribution of melanocytes
Freckles (ephilides)
Actinic lentigines
- another name?
- related to?
- where do they occur?
- elongated RR?
- increase in which type of cell?
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
Why do you get acquired simple naevi?
During infancy the melanocytes : keratinocyte ratio breaks down at a number of cutaneous sites
This allows formation of simple naevi
Neavus development?
Acquired navei develop alon a well-defined pathway:
Junction–>
Compound–>
Intradermal
CDKAN2A gene associated with what?
Familial dysplastic naevi and therefore melanoma
Life time risk of melanoma in cases of familial dysplastic naevi?
Lifetime risk of melanoma up to 100%
Is the epidermis effaced in dysplastic naveii?
No! Unlike melanoma where epidermis is effaced
Dysplastic naevi atypia?
Architectural atypia AND cellular atypia
Host reaction-fibrosis and inflammation
Unlike melanoma epidermis not effaced
Which type of cells do you get in halo navei?
Halo naevi are overrun by LYMPHOCYTES
What type of cells do blue naevi consist of and which layer of the skin are they found in?
Blue navei consist of spindle cells and are ENTIRELY dermal
“benign juvenile nevus”?
Spitz nevus
- consist of large spindle and or epithelioid cells
- most are benign but there is a malignant variant
Which type of cell are spitz navei composed of?
Consist of large spindle and/or epithelioid cells
Four main types of melanoma:
Superficial spreading
Acral/mucosal
Lentigo maligna
Nodular
Where would you find superficial spreading melanoma?
Trunk and limbs
Where would acral/mucosal melanoma arise?
Acral and mucosal (shocker)
Where would lentigo maligna arise?
Sun-damaged face/neck/scalp
Where does nodular melanoma arise?
Varied sites, but often trunk
RGP and VGP of melanomas?
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)
What is the breslow depth?
Deppest tumour from granular layer mm
Melanoma prognosis largely relates to what?
Melanoma prognosis largely relates to Breslow depth and ulceration
What does the suffix “b” mean? e.g. pT3b
Suffix b indicates tumour ulceration e.g. pT3b is a tumour between 2-4mm with ulceration
Malignant melanoma treatment?
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
Which type of melanoma may have c-kit mutations and how could you treat them?
Some acral melanoms may have c-kit mutations and may be treated with imatinib
Melanomas on intermittently sun-exposed skin may have which type of mutation?
Melanomas on intermittently sun-exposed skin may have a BRAF mutation
How can you test for mutations in melanoma?
Can test for mutations on paraffin fixed tissue
BRAF
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
What are dysplastic naevi?
Generally >6mm diameter
Variegated pigment
Border assymetry
