Nevi and Melanoma Flashcards
What is a nevus and what is it very similar to?
Benign, circumscribed collection of cells composed of tissue elements normally present in skin, but in an abnormal amount
- > similar to hamartoma
- > in this case, we are talking about melanocytic nevi which are collections of melanocytes
When do nevi typically appear / stop appearing?
Generally appear during childhood / adolescence, and slowly disappear over the lifetime of the individual
You stop getting new nevi generally by around age 40
What is a congenital nevus / how does it appear? What does it have in it? Why can it be worrisome?
Nevus present at birth, generally slightly raised / pebbly. Often has hair in it.
Variability in color is common, with irregular margins -> can be worrisome for melanoma
Do congenital nevi predispose to cancer? How do you treat them?
Small and medium sized ones do not, but large ones (>20 cm) confer an increased lifetime risk
Treat large ones by skin grafts / expanders, or watchful waiting if surgery would ruin the patient’s appearance
What is a spitz nevus? What color are they?
Nevi of children which were once thought to be melanomas. They are benign.
Colors include pink, red, or brown
What is the typical progression of an acquired nevus on the microscopic level?
- Junctional nevus - melanocyte nests grow at the dermal-epidermal JUNCTION, childhood
- Compound - Nevus cells grow at DEJ and inward into the dermis
- Intradermal nevus - nevus nests lose their junctional component and grow directly into the dermis, adulthood
What is the typical progression of an acquired nevus on the macroscopic level?
- Junctional nevus - flat brown MACULE will well defined borders
- Compound nevus - light BROWN PAPULE
- Intradermal nevus - verrucous (wartlike) tan / FLESH-colored PAPULE.
flat brown -> raised brown -> raised fleshy.
What is a Clark’s nevus also called? Are they premalignant?
Atypical / dysplastic nevus
They are benign, although associated with architectural abnormalities / cytologic atypia which mean that the patient likely has increased overall risk of melanoma
Why are atypical / dysplastic nevi considered atypical?
They are often asymmetric, have irregular borders, variations in color, and can be rather large
What should you do if you see many dysplastic nevi on a patient?
Biopsy the “ugly duckling” of the bunch to confirm it’s benign. Take many photos and look for progression.
Keep in mind removing them does not necessarily change the cancer risk since the mutation causing these is germline in these patients
Is melanoma common, deadly, and who tends to get it (males vs females)?
Most common cause of death from skin cancer.
Occurs more frequently in women (due to tanning), but men tend to die more from it (because they don’t care about their skin and come in at late stage)
What are important risk factors for melanoma?
Fair skin type (blondes and gingers), especially red hair (melanocortin receptor polymorphism)
Xeroderma pigmentosum
Ultraviolent light (like phototherapy -> immunosuppression, as well as formation of ROS / thymidine dimers)
H/o dysplastic nevi or obv melanoma
Do melanoma arise from nevi?
No, generally less than 25% actually arise from existing nevi. It just happens that having more nevi predisposes you to a greater risk of melanoma arising elsewhere
What signs should you look for to differentiate nevus from melanoma?
ABCDE’s
Asymmetry Border irregularity Color variation Diameter >6mm Evolution - change, i.e. bleeding, growth, crusting, symptoms, oozing erosion, scaling, itchiness, swelling etc
Why are the criteria for biopsy of nevi different in children? What does melanoma look like in children?
They tend to not present with typical findings, and often the only change associated is “E”, where they are more likely to bleed.
Children: Amelanotic - uncolored Bleeding bump Color Uniform! De novo, any diameter
