Pigmented lesions Flashcards
Where are melanocytes derived from?
The neural crest
Which conversion does the melanocortin receptor control?
Phaemelanin (red hair colour) to eumelanin (brown/black)
What are ephilides?
Freckles- patchy areas of pigmentation occurring after UV exposure
When do most acquired naevi arise? What is the malignant potential of these?
1st and 2nd decades. Very low
What are actinic lentigines?
“Liver spots”
What is the malignancy risk of large congenital naevi?
Around 10-15%, may need excised
What are the three main features of dysplastic naevi?
Generally >6cm in diameter
Border asymmetry
Variegated pigment
What is the lifetime risk of malignant melanoma in cases of familial dysplastic naevi?
Up to 100%
What group of patients most commonly gets malignant melanoma?
Middle aged people, commoner in females
What are the risk factors for melanoma?
Intense intermittent UV exposure
Pale skin type
Dysplastic naevi
What features may make you suspect melanoma?
Ulceration Bleeding New lesion in an adult Change in shape Irregular pigment Satellite lesions ABCDE checklist
What is the commonest type of malignant melanoma?
Superficial spreading
What are the two growth phases of melanoma?
Radial growth phase- in situ
Vertical growth phase- invasion into upper epidermis and through the basement membrane
How do nodular melanomas behave differently?
No evidence of RGP; may be more aggressive
What does the prognosis of melanoma relate to?
Breslow depth and ulceration
