Case Number : Case 863 - 8th October Posted By: Guest

This looks basically a congenital type of nevus harboring a central worrisome focus made up of junctional spitzoid cells. Mostly nested, with dust-like pigment, and limited pagetoid spread. Patchy inflammation and fibrosis within the subjacent dermis. I am inclined to call this benign. My threshold for MM is usually low, especially in back skin lesions from adults, yet in this particular case I would not move too much away from a combined nevus with likely superficial reactive/repair changes

I assume that this is a dysplastic congenital compound nevus (nevus on special site)
Niether archetictural no cytological features make me worry about melanoma.

Melanocytic lesions continue to be a great problem to pathologists, certainly to me. In my opinion this is melanoma in situ (pagetoid) over intradermal nevus. I think this grade of pagetoid invasion of the epidermis is not allowed in benign melanocytic proliferations.

I also favor the diagnosis of MMIS arisning in the background of compund nevus with congenital features as did Romualdo (especially if there is a history of "mole with changing charecter")

Agree with Romualdo.
The central area of atypical lentiginous proliferation with pagetoid spread is concerning for melanoma in situ, particularly in the absence of any other obvious cause for this (ie no underlying scar or features to suggest trauma).

A simple congenital nevus or a displastic nevus should not have this lentiginous and pagetoid proliferation, so I believe this is a Melanoma "in situ" associated with a nevus.

Melanocytic lesion on the back of a man is always a source of concern, mainly if it is an asymmetric one.
In this case, I found a superficial and deep congenital nevus with pagetoid spread restricted to the center of the lesion and appendageal involvment by lentiginous melanocytic proliferation. I think those and others atypical findings are too focal and slight to be construed as evidence of melanoma. They would be better interpreted as signs of trauma or abnormalities due to flexural location.
I would call this Zitelli's nevus.

People hedging for this being a melanoma can never go wrong as the lesion irrespective of its nature (benign or malignant or uncertain!) has a low risk of metastasis and one cannot know what the true nature of this tumor is, unless it metastasizes. Therefore even if it does not metastasize, you cannot go wrong if you call it melanoma! Folk saying that this is benign have a small chance of being proved wrong if it does metastasize (terrible luck!).

On that statistical basis it would be wise to say that this is a melanoma based on the worrying central pagetoid spread. [u]You cannot go wrong![/u]

For what it is worth (nothing, in the bigger scheme of things!) in my opinion (based on my teachers and the slides I have seen. [url="https://dermpathpro.com/blog/4/entry-114-the-milk-of-human-kindness-and-the-diagnosis-of-melanocytic-lesions/"]Read Dr. Diwan's excellent blog if you haven't already![/url]), the central pagetoid spread of single cells, in the context of a benign looking symmetrical compound nevus, is not a feature that predicts malignancy.

I am not expert with melanoma but I am not pleased with the variable sized nests with some atypia, also the follicular lentiginous component and the pagetoid spread and the scattered lentiginous activity that I can perceive some of them as large cells. I will better call it melanoma in situ evolving on top of a nevus.

Assuming this is representative I doubt very much I'd sign it out as melanoma in practice - even though as Sasi says one can make a clear-cut case! I would certainly admit to some uncertainty i.e. I do not know the biological significance of the changes but given small size and superficial nature of the lesion (and presuming no evidence of a vertical growth phase dermal component in additional levels) would certainly expect benign outcome (fingers crossed!!). Excision looks complete and no further management is required.

Melanoma in situ in the background of a compound naevus

Looks like an in-situ melanoma on a back ground of a nevus. The latter shows some features of a congenital nevus. The melanocytes within the epidermis are non-atrophic.

I agree with philosophy of cannot-rule-out MMIS (or superficially invasive MM if those are similar atypical large Spitzoid cells in the dermis off to the right) with Spitzoid features, arising in a background of congenital pattern nevus. P16 stains may be useful to help support malignant, but only if negative.

A few features that suggest malignancy, taken as a whole rather than just individually:
1. Age of patient. 50+ years is most probably a malignant rather than benign new Spitzoid proliferation.
2. Heterogeneity of cell populations and pigment, and abundant dusty grey cytoplasm.
3. Prominent and chronic pagetoid scatter. I don't think this is trauma related, as pagetoid cells go straight up into the stratum corneum, suggesting a constant, unrelenting pagetoid scatter process.
4. There is a mitotic figure possibly representing a melanocyte (photo resolution limits a proper ID) above the basal layer in the bottom right photo (immediately under the copyright © symbol).
5. Poorly circumscribed and messy lentiginous component.
6. Targeted host chronic inflammatory reaction.

Clinical history might be helpful i.e. recent change in longstanding lesion. But even so, I favour the beginnings of melanoma-in-situ arising in naevus rather than a combined naevocellular and Spitz based on the limited number of images seen. In any case, the prognosis is likely to be excellent.

Excellent discussion!

My diagnosis was: [b]Melanoma in situ in conjunction with a superficial congenital melanocytic nevus.[/b]

This lesion did not extend into the margins of resection.

Dr. Hurt, what did you take into account to diagnose this as melanoma and not as benign congenital nevus with atypical features?

[quote name='Robledo F. Rocha' timestamp='1381282619']
Dr. Hurt, what did you take into account to diagnose this as melanoma and not as benign congenital nevus with atypical features?
[/quote]

Robledo, I keyed off of the disparity between the two patterns in the field. The epidermal component, in part, is very different from the epidermal component in the remainder of the lesion. In effect, there are pagetoid melanocytes in a pagetoid pattern focal in the epidermis, but not like those changes identified in classical irritation effects. Thus, I regarded this small focus as something fundamentally different from the nevus; I regarded it as melanoma in situ. The remainder of the lesion is a superficial congenital melanocytic nevus of the kind described by Ackerman in ~2007.

One [i]might[/i] argue that the epidermal component is just another pattern of a nevus, but nevi don't produce [i]this[/i] pattern, as a rule. In the 1950's and 1960's, many pathologists used the term "active junctional nevus" to refer to a similar histopathological finding, but they admitted that it was the equivalent of melanoma in situ -- so why not just use melanoma in situ? In contrasat, and to take the matter a bit further, Wayte, writing in a book titled "The Skin", in 1971, indicated that no matter how pleomorphic the epidermal component of a melanocytic lesion was, until it was identified as dermal, it could not be considered a melanoma. I consider that position untenable, and I think most would agree with me today.

As for the language of "atypia" (or "dysplasia"), I don't use it, because it is fraught with problems of clarity in communication, epistemological ambiguity, downright obfuscation, and it perpetuates the notion that nevi can be "on their way" -- by their very nature -- to becoming melanomas. When I encounter uncertainties, I simply admit that I am not sure. In this case, I am as sure as I'll ever be that this is melanoma in situ.

I guessed that this would be the answer Dr. Hurt. However, I hope you agree that there is not enough scientific data out there to be objective enough regarding the nature of such melanocytic lesions with conflicting 'opinions'.

Sasi,

I take the opposite approach; I think there is plenty of objective data to indicate that pattern recognition, especially of classical patterns such as this, is sufficient to render a diagnosis with enough certainty for therapy. I have seen many many cases in my career with this pattern that were treated inadequately and with bad results. Furthermore, there is a host of cases that very few see, because they are medicolegal cases outside of the literature. Many of these cases have patterns much more subtle than this one, which, because of [i]lack[/i] of a diagnosis and treatment have killed the patient.

It's funny (i.e., strange), I used to laugh out loud when I saw the cases that Ackerman called melanoma in situ; yet, after some years in practice, I no longer laugh -- because they really [i]are[/i] melanomas in situ, albeit subtle. In my mind the lesion above is not all that subtle.

Yet, I will concede to you the fact of disagreement about the diagnosis of a given case; disagreement of opinion will always be a fact of this discipline. Disagreement about a diagnosis, however, is not the [i]standard[/i] of a diagnosis; reality is.

Mark

I am coming around to Mark's view that dysplastic naevus is often a problematic term (although I am still guilty of using it in many reports!). I think there are many lesions, often in the elderly, which in reality are low grade melanomas, as confirmed by the clinical behaviour of slow and steady change/increase in size, which to my mind is not really compatible with naevus. Lentiginous melanoma is one example. I think many of these lesions are being signed out as dysplastic naevi by the majority(?) given the lack of significant cytological atypia or clear-cut histological criteria for malignancy, but where clinicopathological correlation including dermoscopic monitoring is helpful. The prognosis is usually excellent, but the reality is still that these are still likely to be melanomas, a small proportion of which become aggressive.

Both of you might very well be right. However, the point I am making is that the reason melanocytic lesions are so controversial is because there not enough scientific papers out there to prove or disprove either theory. Thus we are having to rely on the opinion of 'experts' and it is well known that there is huge disparity even between 'experts', when it comes to borderline lesions.

As a scientifically trained doctor it does make me uncomfortable not to be able to be objective about an important diagnosis like a melanoma. In evidence based medicine [url="http://www.eortc.org/sites/default/files/POL019%20v%201.01%20NS.pdf"]'expert opinion' is a level 4/ Grade C (least preferred)[/url]. However, given the complexity of parameters used to judge melanocytic lesions, I am not sure if we are ever going to be able to be more objective about the diagnosis!. It might be safer to call all melanocytic lesions which are not benign- malignant and grade the risk and treat/ follow-up accordingly.

Sasi,

Part of the problem with proving or disproving any theory is the development of objective language applied to such lesions. I argue that this is why Dysplasia and Atypia should be abandoned; these are abstract terms than cannot be applied consistently and, as a consequence, result in "theories" that cannot be applied or understood consistently.

Yet, even with this problem, I don't think it is necessary or desirable to automatically acquiesce to calling a melanocytic proliferation a melanoma when one isn't sure of the diagnosis. Rather, these are the very cases that require intensive study to understand their nature. Some are melanomas; some are nevi -- and some will still be unknown and awaiting for the next round of technology to help uncover their nature. Yes, most, if not all of these lesions will need to be excised, but this is not the same as admitting that all are melanomas -- that has to be proven, even if by difficult and highly technical methods. It is indeed a question for science and not solely for opinion.

Mark