Atypical and dysplastic nevi: do you need to remove them?

In this article, we define these nevi, and also figure out if everything is so scary.
Let's start this material with the classic situation that has become.

A person comes to an appointment with a doctor (dermatologist or oncologist), shows him moles.

And then there is something like this dialogue:
– You have dysplastic nevi here, here and here.
– What is it? Is it dangerous?!
– Dysplastic nevi are such moles with an uneven edge and a non–uniform color. Dysplastic nevi can turn into melanoma, so they need to be removed.
– Oh!!! How scary!!! Let's delete it soon!!!

Moles are safely removed, sent for histology.

A person comes home and starts reading on the Internet about dysplastic nevi аnd there they add fuel to the fire:

  • Dysplastic nevus is any nevus with an uneven edge, uneven coloring.
  • All dysplastic nevi turn into melanoma in 100% of cases.
  • To prevent death from melanoma, you need!!! URGENT!!! remove all dysplastic nevi.

All this "beauty" has been rewritten from one site to another for many years and overflows the Internet to the brim.

Let's deal with all this from the point of view of evidence-based medicine.

What is dysplastic nevus?

The most important thing to note here is that dysplastic nevus is a histological diagnosis. This means that it is possible to understand whether you have a dysplastic nevus or a normal one only after the removal of the formation. This diagnosis is made by a pathologist when studying a biopsy of a removed mole, based on strictly defined criteria.

The diagnosis of "dysplastic nevus" cannot be made with a simple visual examination.

Why then do many doctors scare us when examining dysplastic nevi? Because in dermatooncology, the concepts of "dysplastic" and "clinically atypical" have been mixed for a long time.

What is the difference?

Clinically atypical nevus – what is it?
There has been clarity here since 1990, when the International Agency for Research on Cancer (IARC) defined what should be called an "atypical nevus".
"
At least part of the nevus must be represented as a spot, in addition to this, at least 3 of the criteria listed below must be present:
  • fuzzy border;
  • size 5 mm or more;
  • different colors in coloring;
  • uneven contour;
  • redness of the skin.
Of course, there is some subjectivism in this definition, because the concepts of "fuzzy border" and "uneven contour" leave room for free interpretation. At the same time, pay attention to the number of criteria (4) required to establish the diagnosis of "atypical nevus".
"
Atypical nevus is a diagnosis on examination, visual.
Dysplastic nevus is a histological diagnosis, after removal.
4 examples of atypical nevi [3]. All four formations, except D, have 4 criteria:
  • A component in the form of a spot.
  • Size is more than 5 mm.
  • Fuzzy borders.
  • Different colors in coloring.
The formation has a D – shape in the form of a spot, the size is more than 5 mm, fuzzy borders + an uneven contour.

How dangerous are dysplastic nevi?

Here are concrete and proven figures, which it would be better to get acquainted with those who are throwing a tantrum on the Internet.

  • The annual risk of turning a dysplastic nevus into a melanoma is 1 in 10,000. According to the authors [4], this is very little.
  • About 70% of melanomas develop not against the background of nevi, but against the background of unchanged skin [5].
  • A study of the genetic profile of atypical nevi has cast doubt on the hypothesis that they are precursors of melanoma [6].
  • In two studies, the authors observed patients with partially removed, histologically confirmed dysplastic nevi for a long time (up to 17 years) [8,9]. Based on this, the very thesis of an increased risk of developing melanoma from a dysplastic nevus can be seriously questioned.

Delete or not?

We were unable to find practical recommendations in which the presence of an atypical nevus on a person's skin itself would be considered a direct indication for its removal.

On the other hand, the presence of both single or multiple, as well as atypical [7] and dysplastic [3] nevi on a person's skin equally increases the risk of developing melanoma on the skin as a whole.

Thus, the most logical tactic is not the preventive removal of atypical nevi, but an increase in the frequency of preventive self-examinations and examinations by an oncologist.
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