What is Dermatopathology?

Dermatopathology (dermato = skin; pathology = a study of disease):  the medical discipline whose practitioners study and make judgments about the diseases of the skin by means of evaluating through a microscope the histopathological structure of lesions in cutaneous biopsies and excisions.  The discipline also includes studying skin diseases by means of histochemistry, immunohistochemistry, electron microscopy, and molecular biological techniques when necessary.  Those who practice dermatopathology usually have an MD or DO medical degree but may also have other credentials.

Dermatopathology Standards

. . . it must be remembered that a technical standard can never be substituted for one's judgment of the facts, i.e., a diagnostic standard. The diagnostic standard requires that the information from each case be integrated fully and the clinical context be considered carefully prior to drawing any conclusions. The diagnostic standard is the ultimate purpose of any technical standard, and dermatopathologists must not allow themselves to use the latter as a justification for abdicating their responsibilities as interpreters of and decision makers about complex medical information.


Mark A. Hurt, MD

in reply to the question of "Dermatopathology Standards"

Whither Dermatopathology?

What is a diagnosis?  The term means literally to "know across."  The Oxford English Dictionary defines it as the "determination of the nature of a diseased condition; identification of disease by careful investigation of its symptoms and history; also the opinion (formally stated) resulting from such investigation."  In the modern era of medicine, the "tried and true" approach to understanding a disease consists of observation, comparison, more observation, more comparison, review of previously gathered data, review of literature, acquisition of additional data, re-review, and, at some point, integration of all the data into a cohesive whole.

 
In the process of investigation, the history of medical knowledge has been one of induction to a principle, then the application of the principle to new observations, comparison of the new observations to the established principle, modifying it if necessary, and so on.  The systematic and formal process of this act is the scientific method.  Thus, what began historically as a philosophic approach to data, primarily an empiric one, developed into a formal systematic approach to classifying the data, resulting ultimately in scientific principles about how a biologic system (in the case of medicine) worked.
 
In this context, the microscope was simply a logical extension of one's eyes in the process of classifying a different aspect of the same clinical observation in the skin.  The microscope did not supersede clinical observation; it served rather as an adjunctive device, yielding a new body of data that had to be integrated into an ever expanding body of concepts or principles.  Similarly, the discovery and applications of immunologic principles as well as the applications of electron microscopy to morphology-based diagnosis have also been adjuncts to the process of establishing a diagnosis when applied with a thorough knowledge of dermatopathology, in turn applied in a proper clinical context. . . .
 
Clinical dermatology and dermatopathology are fundamentally cognitive professions; therefore, they require the ability of concept formation, concept integration, and complex interpretation of data that cannot be replaced easily by the introduction of a new technology as such.  A diagnosis requires a highly sophisticated type of data processor and data integrator:  an extensively trained and experienced rational human mind. . . .
 
Whither dermatopathology?  Dermatopathologists are physicians; as such we owe it to ourselves to become educated in the history of our profession, to master current technologies, and to exploit relevant newer technologies while holding a proper context in order to learn as much as possible about the natural history of disease - likely with microscopes but without them if necessary - as a rational use of technology will offer us more insight into the diagnostic process.
 
We and our patients deserve no less.
 
Mark A. Hurt, MD
 
Excerpted from:  a reply to "Whither Dermatopathology?"

Dysplastic Nevus? -- There is no such nevus.

No one knows the mechanism(s) by which a melanocyte within control skin or within a melanocytic nevus becomes the nidus of a melanoma.  This is why the designations ‘‘precursor’’ and (even worse) ‘‘premalignant melanocytic dysplasia’’ are so problematic.  By the time one recognizes a given lesion for what he thinks it is, its nature is already determined and, in most instances, diagnosable. . . .

 
The real challenge diagnostically is whether one can differentiate particular patterns of melanocytic nevi from the melanomas that mimic them.  One can, with experience, do this in most cases.  The pathologist is thus able to identify a given melanocytic lesion as a melanocytic nevus, a melanoma, or a melanocytic nevus occurring in association with a melanoma.  The fourth possibility is that one cannot assign the lesion to any of these categories; that is, the status diagnostically is uncertain (melanoma cannot be excluded) and should be stated as such in the pathology report.  In nature, of course, there are only three possible diagnoses:  melanocytic nevus, melanoma, or melanocytic nevus in association with melanoma.
 
Mark A. Hurt, MD
 
Excerpted from:  The melanocytic nevus described by Clark et al.  What is its nature?  What should it be named?  An answer from history and from logic.


 

Types of melanoma?

. . . the problem with the diagnosis of melanoma is the diagnosis of melanoma.  Melanomas have different patterns, often in the same lesion; the diagnosis and margin definition often are difficult to establish regardless of pattern in a given tumor; and the prognosis for a given patient is not understood simply by applying a ‘‘type’’ with a Breslow measurement, a Clark level, and commenting on the presence of ulceration -- and it never will.  Why is this?  It is because each melanoma plays out in its own way if given enough time, given any particular patient’s immune status and context clinicopathologically.

Mark A. Hurt, MD

Excerpted from:  Types of melanoma?
J Am Acad Dermatol 2008; 58:1059-1060

Diagnosis

Diagnosis, ‘‘the art or act of identifying a disease,’’ literally ‘‘across knowing’’ or ‘‘through knowing’’, is a concept that refers to the identification of a specific disease that the observer accomplishes by evaluating criteria and understanding that certain essential criteria are present in a given case for the purpose of effecting a given treatment (or no treatment).  For one to establish a diagnosis, one must ‘‘know through’’ a set of criteria that are derived inductively from the observation of actual patients (including their biopsies) to determine which criteria matter—in fact, which are fundamental—and which do not. These criteria are then applied deductively to new cases to identify new examples of the same type or class of diagnosis. The inductive, then deductive, process directs (in fact refines) one to the fundamentals of the diagnosis.
 
Mark A. Hurt, MD
 
Excerpted from:  Diagnosis! (Not Prognosis, Not Potential, Not Risk)


Melanocytic Nevus vs Melanoma

The example of melanocytic nevi existing as a continuous spectrum to melanoma is, in my opinion, the most notorious example of illogical thinking that exists in the field of dermatopathology.  Yes, it is true that some melanocytic nevi can mimic melanomas morphologically, and, yes, it is true that the opposite occurs.  It is even true that some melanocytic nevi occur in conjunction with melanomas and can be diagnosed as such.  It is not true, however, that melanocytic nevi ‘‘convert’’ or ‘‘transform’’ into melanomas or that the natural history of a melanocytic nevus is to become a melanoma.  If this were true, one would need no concept of melanocytic nevus; all melanocytic neoplasms would be melanomas (which they are not!).
 
Mark A. Hurt, MD
 
Excerpted from:  Diagnosis! (Not Prognosis, Not Potential, Not Risk)

A "Right" to Health Care?

. . . there is no right to health care except by producing it or trading for it, else it will cease to exist – and so will your diagnosis. Without your rights secured, your diagnosis will matter no longer – because it will not be a diagnosis.

If your diagnosis is at stake, then your life is at stake as well as the lives of every individual you love. If you care about your diagnosis, then don’t allow the Rights of Man to be infringed further without a fight.

If you wish to live as a human being, then help return the practice of medicine to the private practice of medicine.

Mark A. Hurt, MD

Excerpted from:  Selfishness at the Microscope: Your Diagnosis or Your Life.

A speech delivered at:  Redeeming Reform:  What Health Care Reform Could Be and Ought to Be.  A Briefing at the National Press Club, Washington, D.C., May 10, 2010.  Sponsored by Americans for Free Choice in Medicine.