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Uncertainty in Diagnosis

Dumas, Alain MD

The American Journal of Dermatopathology: December 2010 - Volume 32 - Issue 8 - p 859
doi: 10.1097/DAD.0b013e3181dd4e66
Letter to the Editor

Dianon Systems, 1 Forest Parkway, Shelton, CT.

To the Editor:

Mark A. Hurt is opposed to statements such as Elder and Xu's “Melanocytic Tumor of Uncertain Malignant Potential1” because “a diagnosis is a statement of certainty,” whereas “certainty is a concept that refers to the identification of facts that, taken together, mean something specific, given a context of knowledge in a given discipline in a given timeframe in which the knowledge was discovered.2” Does Dr. Hurt believe that a competent astrologist's report deserves the label of certainty? The “Hurt's certainty” of Hurt looks like belief to me. Although it would be nice to know what was in physicians' minds when they diagnosed melanomas, ordered and performed amputations for lesions now called Spitz nevi-some may have been skeptical as the well circumscribed Spitz nevi do not look clinically like typical melanomas-this is not the Psychology Review. The identification of typical histologic features of melanoma means malignancy in our accepted standard of practice, but we cannot know how many of our “melanomas” are benign lesions having acquired after UV exposure, trauma, or inflammation, misleading histologic features of malignancy, or how many of our “nevi” are nevoid melanomas excised by a wise dermatologist before metastatic spread. Melanocytic Tumor of Uncertain Malignant Potential is not a statement of certainty but a statement of truth, unfortunately of limited value. A diagnosis of malignant melanoma means a range of outcomes, that is, the difference between “malignant” and the statements of risk or potential such as “Uncertain Malignant Potential” Hurt want to banish as meaningless is not that big. The practical difference has shrunk because melanoma excisions are more conservative, adjuvant systemic agents have yet to be successful, and denial of insurance coverage for pre-existing condition is now prohibited in the United States.

Hurt defends the benign/malignant dichotomy against “the premise that all diseases exist on a spectrum and that the terms “benign” and “malignant” should be relegated to the dustbin of history to be replaced with the term “low risk”, “high risk” and various risks within these 2 extremes. Worse yet is the preposition that the spectrum consists of benign neoplasms “transforming” into malignant ones, which is a sure sign of a mind out of focus.2” My wife applauds the diagnosis but I still believe that congenital nevi can occasionally transform into melanomas. I even believe that these concepts-the benign/malignant dichotomy, the low-risk/high-risk spectrum-are too focused. I would say that neoplasms come in different flavors and that a good/bad dichotomy or a faint/strong spectrum are insufficient. The malignant Spitz tumors we cannot reliably identify seem different than conventional melanomas of same Breslow depth or same level of nodal involvement. Prognosis and mutations are not the same. Ackerman's dichotomy-Spitz nevus/melanoma-is reductive.

The next article in the same issue illustrates perfectly why uncertainty should be emphasized. Mistakes happen, even to great pathologists. In the lawsuit, the plaintiff experts often deny uncertainty. In Ackerman case a focus a melanoma in a benign nevus, they stated that the patient had a “85.6% chance of 8-year survival” and a “98% chance of cure.3” If they know so much why don't they provide such details in their own diagnostic reports? In a lawsuit I witnessed, an unknown “expert” provided a precise growth rate and quite high chance of survival had the melanoma been diagnosed some 4 months earlier at the first opportunity to do the biopsy. Instead of waiting for congressional action on medical malpractice, American Societies of Dermatology and Dermatopathology could evaluate the state of uncertainty in prognosis and diagnosis. Like the authorities occasionally trying to smuggle forbidden items through the controls, they could also disguise as another consultation slides of routine or difficult cases with known outcomes and establish average and individual error rates teaching a precious lesson especially to the weakest among us. Uncertainty should be acknowledged, evaluated, and reduced instead of hidden, ridiculed, or denied. This evaluation is difficult. Excision of nevi or melanomas for histologic evaluation influences their history in a manner reminiscent of Heisenberg uncertainty principle. However, molecular pathologists may be able to look for markers of melanomas in archival blocks and evaluate our false-positive and false-negative rates. The Hurt's distinction between diagnosis and prognosis, potential, or risk is spurious. Only indicating a risk, tuberculin test, HIV-1 enzyme-linked immunosorbent assay or Venereal Disease Research Laboratory test are proper diagnostic tools because they are evaluable (relative costs, risks, sensitivity, and specificity indicate whether they are used as screening or confirmatory tests or superseded) and correspond to modern concepts of pathophysiology. Charlatans, shamans, traditional healers do make diagnoses, but their approach lack these features. On which side are we?

Alain Dumas, MD

Dianon Systems, 1 Forest Parkway, Shelton, CT

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1. Elder DE, Xu X. The approach to the patient with a difficult melanocytic lesion. Pathology. 2004;36:428-434.
2. Hurt MA. Diagnosis! (not prognosis, not potential, not risk). Am J Dermpathol. 2009;31:763-765.
3. Schoppe CH, Sangueza OP. Musing on matters medical-legal: a missive in remembrance of A. Bernard Ackerman, MD. Am J Dermpathol. 2009;31:766-768.
© 2010 Lippincott Williams & Wilkins, Inc.