Pathology of pigmented lesions Flashcards
Where do melanocytes originally come from?
neural crest
In early embryogenesis, where do melanoblasts migrate to?
Skin
Uveal tract of the eye
Leptomeninges of the spinal column
What does the MC1R gene do?
Determines balance of pigment by turning phaemelanin into eumelanin.
What does 2 defective copies of this gene cause?
Red hair and freckles!
What are ephilides?
freckles
What causes ephilides?
One defective copy of the MCR1 gene
What are liver spots known as?
Actinic lentigines
Where are liver spots most common at?
Face, forearms and dorsal hands.
What causes melanocytic naevi?
The melanocyte: keratinocyte ratio breaks down so more melanocytes.
What is a sporadic dysplastic naevi?
> 6mm diameter with variegated pigment and has no familial link
True or False
Familial dysplastic naevi have a strong link with developing melanomas
True
True or False
Malignant melanomas are more common in females.
True
What type of melanoma affects the trunk and limbs ?
Superficial spreading
What type of melanoma affects sun-damaged face/head/scalp?
Lentigo maligna
What type of melanoma affects the mucosa?
Acral/mucosal lentiginous
What does RGP stand for?
Radial growth phase.
E.g. macules in-situ
Why do VGP melanomas metastasise?
Blood and lymphatic access.
RGP melanomas are restricted to the epidermis.
How does nodular melanoma differ from other melanomas?
Begin as a nodule as opposed to a macule/patch.
Much more aggressive.
What is prognosis related to?
Breslow thickness of tumour
what does in-situ mean?
100% survival since cancer cells are present but no melanoma is yet present.
How thick is a stage 2 tumour?
1-2mm. v
it has an 80% survival rate.
How thick is a stage 4 tumour?
> 4mm thick.
20% survival
What does the suffix -b mean in staging?
Presence of ulceration
Describe the spread of malignant melanomas
- dermal lymphatics.
- regional lymph node metastases
- blood spread to heart, lungs, GI tract, brain.
