Nevi and Melanoma Flashcards
What is a nevus?
Also called a mole or melanocytic nevus is a benign congenital or acquired proliferation of melanocytes. They are classified based on clinical presentation and histological aspect.
Lenigo: a single proliferaion of a melanocyte, no presence of any nest.
Junctional nevus: formaion of a nest at the dermo-epidermal juncion, but it is lat.
Compound nevus: a mix between juncional and dermal nevus Dermal nevus: no presence of any nest but melanocytes proliferaion in the dermis ➔ A nest is an aggregaion of at least 3 melanocytes present at the dermo-epidermal junction.
What is lentigo?
Also called freckle is a small flat light or black colored macule that cane be acquired or congenital and measure a few mm.
Clinically indisinguishable from a juncional nevus, you must check the histopathology.
It can be a sign of systemic syndromes:
Peutz-Leghers Syndrome: hamartomatous polyps in the gut that can cause cancer. Clinically, we see muliple freckles around the mouth and the genitals.
Noonan Syndrome: It was called Leopard Syndrome in the past. It has the same manifestaions as Peutz-Leghers, but it occurs with cardiac malformations.
What is a common acquired nevus?
This is banal, the most found in our body (trunk and limbs
paricularly). They are round/oval and symmetrical uniformly pigmented lesions with a diameter<6mm. We have around 15-30 of them on our body. They are juncional or compound nevi.
Miescher nevi: localized on the face. They are light brown or skin color dome-shaped nevi. They have dermal and/or juncional components. It can grow but will remain benign. It is more of an aestheic problem.
Unna: It mimics fibro-papilloma, it’s a sot nevus localized on the neck
and trunk (axilla), at the level of the dermis.
What is an atypical nevus?
Also called Clark nevus or dysplastic nevus. It is neither banal nor common. It is asymmetrical with irregular edges and is not uniform in color. Its size is >6mm.
It is dome-shaped in the center (where it has the histology of a
compound nevus)
It is lat at the periphery (where it has the histology of a juncional nevus), looking like a fried egg.
It can be a marker of melanoma, especially in families with muliple atypical nevi (high risk of malignancy). Sporadic forms also occur (but the risk is lower), the risk increases with the number of nevi (>50).
What is a spitz nevus?
Also called epitheloid nevus or spindle cell nevus. It has round
epithelioid and spindle shape cells and is commonly found in children and young adults.
It mimics melanoma from a histological point of view, and the
differentiation is quite hard to make. It is this kind of nevus who is responsible for the many lawsuits we talked about before.
The clinical presentaion is benign most of the ime, especially in childhood. It appears as a red or pigmented lesion on the face.
What is a reed nevus?
It has the same characterisics as the Spitz nevus but is found
in adults. The diferences are that you only find spindle cells in the nevus and the color is black.
It can scare the paient because it grows quite fast.
Its borders are well-defined. It paricularly affects the lower extremities and the female sex.
It also mimics melanoma but can be histologically disinguished from it, even if it is not easy.
In the dermatoscopic picture, you can see a starburst patern that is
specific to this nevus, it looks like a star explosion.
What is a congenital nevus?
It is a hamartoma, as it is a malformaion. They are
divided into 3 types:
Small: <1,5cm, there is almost no risk of melanoma.
Medium: 1,5-20cm.
Large: >20cm, there is a 5 to 20% risk of developing melanoma.
What is a blue nevus?
It can be congenital or acquired, paricularly found on the
back of the hands, the feet, and the butocks. The blue color is due to the Tyndall effect, the melanocytes are localized deep in the dermis. It is benign.
Mongolian spot: Type of blue nevus that occurs on the
lumbosacral area of oriental people at birth or within the 1st year
of life. It appears as one or several bluish lat lesions that can
regress within 10 years.
OTA: Blue nevus that you ind on the face and more precisely on
the periocular space.
ITO: blue nevus that you find on the
deltoid area. They persist for life and have a small risk of
degeneraing into melanoma.
Other variants of nevi?
SUTTON: Nevus surrounded by perinevic viiligo, which is an achromic area. There is an inlammatory reacion that tends to attack the melanocyte, leading the nevus to disappear leaving an achromic lesion.
MEYERSON: It is a nevus surrounded by a halo of eczema.
COMBINED: It is a combinaion of 2 different types of nevi that can seem worrisome for patients but is benign.
RECURRENT NEVUS: It arises at the site of surgical excision of a previous nevus. The excision has not necessarily been incomplete. It can be typical of melanoma when they have been evolving for a while.
Epidemiology and risk factors of melanoma?
10/100,000 people with melanoma in Italy. It is deadly it if treated at an early stage it is 100% curable. The peak is between 40 and 60 years old and it is most common in men. Melanoma can arise de novo 60/80% or nevi degeneration 20/40%.
Endogenous risk factors include : familial and personal history, CDKN2A and CDK4 tumor suppressor genes, number of nevi, light eyes skin and hair.
BRAF gene mutation is the most common.
Exogenous risk factors include : sunburns in childhood, sun exposure intense but intermittent, tanning beds and sun lamps.
Other risk factors include furocoumarins found in citrus fruits.
Protective factors include antioxidant lycopene found in tomatoes, sulforaphane found in broccoli flowers and green tea extract.
How can we diagnose melanoma?
ABCDE rule : asymmetry, border regularity, color (multiple colors in melanoma), diameter (greater than 6 mm in melanoma), evolution.
What are the phases of melanoma evolution?
Radial or horizontal growth phase. The melanoma spreads into the epidermis. We should diagnose every melanoma at this stage to cure 100% of them.
Vertical growth phase. The melanoma spreads into the dermis. It occurs ater months or years of radial growth. The deeper the growth, the worst the melanoma.
What are some variants of melanoma?
Superficial spreading : most common in caucasians, peak in 40 to 50 year olds and predilection for lower extremities in women and back in men. Lesions is to be diagnosed when still flat.
Nodular melanoma : Worst type of melanoma. Horizontal phase is very short or even absent. It grows deeply fast. 15% to 30%.
Lentigo maligna melanoma : Best melanoma as it grows slowly, may find it on the face and grows in over 70 year olds. Only melanoma where risk factor is chronic sun exposure.
Acral lentiginous : More typical of black and oriental people. A subtype is nail melanoma.
What are some rare types of melanoma?
AMELANOCYTIC MELANOMA : There is no pigmentation of the lesion, so it is difficult to think about melanoma; this is a tricky disease.
HALO MELANOMA: It presents with an achromic area surrounding the melanoma. Then, it metastasizes around the primary lesion.
VERRUCOUS MELANOMA: It looks like a wart, but as the lesion
grows, we must think about something else.
OCULAR MELANOMA: Can occur on the conjunctiva, the uvea.
Some scienists pretend the prevalence is increased because of
the use of mobile phones but this theory still must be confirmed.
What are some type of nevi that lead to melanoma?
Atypical(=dysplasic) nevus. This occurs paricularly in the familiar form of the disease. As the lesions don’t respect the ABCDE rule to decide whether they are benign or not we use the SIGN OF UGLY DUCKLING. It consists in looking at the muliple lesions and noticing the one(s) that are diferent from the others.
Congenital giant nevus (to recall, they are >20cm in diameter).
Common nevus (like Unna nevus).
Nevus spilus, which are flat brown macules with muliple nevi inside.
