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Diagnosis versus Prognosis

Mark A. Hurt MD


Dermatopathologists are in the business of diagnosis, not prognosis. Consider that we observe findings under a microscope and formulate those findings, with clinical information, into a concept of a disease -- a diagnosis.

It is true that many times we use special stains to gather more information about the findings in the tissue. Some of us, in specialized practices, take it as far as learning detailed genetic information on specimens from patients. Yet, this does not tell us prognosis; it tells us about the pathologic changes in the tissue -- i.e., the diagnosis, even with the addition of clinical information.

Why is this distinction important, and why is it difficult? It is important because what we do as dermatopathologists does not extend beyond certain parameters; it is difficult because there is a natural tendency for those of us who practice dermatopathology to believe that we can extend our knowledge beyond those parameters. As dermatopathologists, we diagnose; we cannot offer a prognosis. We are not in a position to offer a prognosis.

I have written more about this elsewhere (see reference), but the essence of what I said there, I repeat here. It is this: prognosis is contained in the diagnosis, but the specific outcome is not determined by a single case. Prognosis is determined by gathering cases of a diagnostic type and finding out what happens in the future. Prognosis is implied in the diagnosis, but not determined in a given case.

The next time you read about a diagnosis with an "uncertain malignant potential," keep in mind that this is the wrong way the state the problem. The way to state it is as follows: "this patient has a diagnosis with a range of outcomes, but I do not know exactly how this particular lesion will effect the specific outcome in this particular patient."

As I know this is a highly charged position, I welcome comments.


Hurt MA. Diagnosis! (not prognosis, not potential, not risk). Am J Dermatopathol. 2009 Dec;31(8):763-5. doi: 10.1097/DAD.0b013e3181bbc717. PubMed PMID


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