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An evasive diagnosis is not a diagnosis at all!

Robledo F. Rocha



Melanocytic lesions always represent diagnostic challenge. Some nevi might display features disquieting enough to be unskillfully misdiagnosed as melanoma. And some melanomas have too subtle malignant characteristics that can pass unnoticed if a careful scrutiny is not accomplished. Not surprisingly, some melanocytic lesions are so difficult to be rendered as benign or malignant that even worldwide recognized experts in the field fail in achieve a reproducible diagnosis.

During a recent practical discussion on a small-sized melanocytic lesion, some non-expert pathologists, admittedly frightened of an onerous litigation, thought it would be more prudent to label the case as an atypical melanocytic proliferation, or anything of the sort. Others, avoiding being compromised to a specific diagnosis and its implications, sheltered themselves under the sophisticated acronym SAMPUS (superficial atypical melanocytic proliferation of uncertain significance).

In fact, the presented lesion was originally signed out as SAMPUS, and was managed watching and waiting until a metastasis at last proved it was a thin melanoma.

As seen, both suggested evasive pathways may offer a short-term solution to the pathologist, but an uncomfortable feeling of unfulfilled mission will remain because those gray zones do not provide to the clinician and to the patient any alternative other than an expectant approach, praying that a metastasis never happens.

An evasive diagnosis is not a diagnosis at all! A lesion must be benign or malignant, never something intermediary!

So, what should a pathologist do when feel himself / herself not completely confident to make a diagnosis with surety of a problematic melanocytic lesion?

It does not seem to be the best option acting as a cytopathologist in doubt, who reports a cervical cytology as ASCUS (atypical squamous cells of undetermined significance) and recommends pap test repetition six months later.

So, what about making clear that you don't know the correct diagnosis and referring the case to a renowned expert? It's not different of making an evasive diagnosis since an evasive diagnosis really means an I-don't-know diagnosis.



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Mark A. Hurt MD


Stimulating essay, Robledo!

One thing I should like to say about an "I don't know" diagnosis is that it's honest and unequivocal; it provides the epistemological status of the observer -- but it doesn't provide a real diagnosis. In my experience, when I simply admit that I don't know what the diagnosis is (and I favor either melanoma or nevus based on certain criteria), many of these cases go to genetics if there is enough of a dermal component to evaluate the lesion genetically. In some cases an definitive answer will come out of that analysis. Unfortunately, sometimes not.

There is a tendency in the SAMPUS literature for the diagnostic burden to be placed on the [u][i]lesion[/i][/u] rather than the diagnostician; this is what I call an "inversion" error in logic. The SAMPUS approach inverts the proper order and attempts to make categories for lesions that are "in between" what they really are,

In reality, the burden of diagnosis is the responsibility of the diagnostician, not the lesion. All of the approaches to diagnosis that confer a "borderline" lesion or a lesion that is "one its way" to becoming something else are misguided. The lesion is [i][u]something[/u][/i] at the time there is an attempt to establish the diagnosis. One cannot diagnose a "borderline" this or an "on its way" that.

Yet, what is one to do about "I don't know?" My approach is to describe the lesion as a "melanocytic proliferation", explain that I don't know the diagnosis, favor one or the other based on the criteria at hand, and offer possibilities of how to narrow achieve the diagnosis via consultants or other technology -- and that's about it. In my book, "low malignant potential", SAMPUS, and MELTUMP simply simply don't cut the muster.
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As evident from my previous discussions, I have no problem with Meltump/ SAMPUS etc as i see no difference between these terms, which to me imply 'I don't know'. I don't see it as putting the burden on the tumor, as it is the pathologist that is saying that he/ she is uncertain of the significance. It is not that the pathologist is saying that the tumor is uncertain of its own significance!!!

I agree that if one isn't sure about the diagnosis., it is very important to take the opinion of someone else who you respect. However, it is still an opinion and in difficult cases SAMPUS or 'I don't know' (which I consider synonyms) are perfectly alright to summarise one's report, AS LONG AS, one doesn't consider them as diseases in themselves!!

Diagnosis is an opinion of the expert. Disease is a distinct entity!
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Mark A. Hurt MD


Sasi, I know we don't agree on this regarding SAMPUS and MELTUMP, but my point is valid. Let me show you an another kind of example.

Look at this title:

[font=arial,helvetica,sans-serif]Scolyer RA, Murali R, McCarthy SW, Thompson JF. Histologically ambiguous ("borderline") primary cutaneous melanocytic tumors: approaches to patient management including the roles of molecular testing and sentinel lymph node biopsy. Arch Pathol Lab Med. 2010 Dec;134(12):1770-7. doi: 10.1043/2009-0612-RAR.1. Review. PubMed PMID: 21128774.[/font]

[font="arial, helvetica, sans-serif"]​Now, I challenge anyone about the issue of what is "ambiguous" here. A neoplasm cannot be ambiguous; it just [u][i]is[/i][/u]. Furthermore, there is no such thing as a "borderline" melanocytic tumor. The tumor just [u][i]is[/i][/u]. It has a natural history whether one knows it or not. Ambiguity and "borderline" are epistemological conventions used for uncertainty. Yet, in this example, the authors have reversed it. The way they state it, It is as if the lesion itself is ambiguous or borderline.[/font]

[font="arial, helvetica, sans-serif"]Mark[/font]
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Dr. Hurt. Nowhere in the article did they say that the neoplasm itself is ambiguous. The authors clearly imply that the interpretation of the histological findings is ambiguous because the features are neither definitely benign nor malignant. In fact in my humble opinion you have falsely accused the authors when[url="http://www.archivesofpathology.org/doi/pdf/10.1043/2009-0612-RAR.1"] even in their abstract[/url], they have clearly explained their what they mean by the title.

I think it is just a question of perspective & interpretation. That is what I mentioned earlier- [u]as long as one understands how to interpret the diagnosis made by the pathologist, the term can be used[/u]. I think most dermatologists know what the pathologist means by MELTUMP or SAMPUS etc i.e. that the pathologist isn't sure about the diagnosis. I am unaware of a single dermatologist who interprets the diagnosis to mean that the tumour itself does not know! Certainly not in the UK!

Therefore I do not believe it is worth journal/ mind-space to debate on this topic, as it does not really matter in clinical terms.
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Mark A. Hurt MD



I don't mind dropping the topic, but also I don't agree that this distinction is as clear in the minds of many as you might think.

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