What Is a Pathologist?

While you may never meet one, a pathologist can impact your medical care in important ways. Here’s how:

Several years ago, a contest sponsored by Yale Medicine’s Department of Pathology invited local middle-school students to answer the question “What is a pathologist?” in order to win a powerful microscope.

“I still laugh at the answers we got,” says Jon Stanley Morrow, PhD, MD, Raymond Yesner Professor of Pathology and chair of the Department of Pathology at Yale School of Medicine. “One answer was: ‘Almost as hard a job to get as working at McDonald’s.’ Another said: ‘Doctors check you when you are alive, pathologists check you when you are dead.’”

As for the right answer? Below, Dr. Morrow explains how pathology shapes the care that Yale Medicine provides to patients.

What is a pathologist?

Pathology is a diverse field with many subtypes. Here at Yale Medicine, we have mainly anatomic pathologists, who specialize in looking at tissue through a microscope. Our pathologists are also subspecialty pathologists who are experts in understanding the basis and diagnosis of different kinds of disease, typically categorized by organ types. You tend to have this level of pathologists only at academic centers like ours.

We now have pathologists who specialize in genomics and molecular pathology, a new specialty. There are lots of other types, too, including experimental pathologists, who are scientists; pathologists who do autopsies; forensic pathologists; and clinical pathologists, who run clinical labs.

Are pathologists directly involved with caring for patients?

Absolutely, our work has major consequences for patients in that we guide the diagnostic process, working as an important part of the clinical team with physicians, internists, surgeons and radiologists. In fact, you’ll sometimes hear a surgeon say, “I’m only as good as my pathologist.”

It’s a heavy responsibility, but a rewarding one. The stakes are high. We don’t work with minor illness; we see really serious, complicated illnesses, and we frequently see rare ones. So we treat many patients. When a person has a very serious illness, the course of treatment will most likely be driven by the pathologist’s assessment. The decisions of pathologists and the clinical laboratory guide the majority of health care expenditures in this country.

How do pathologists interact with other doctors?

In pathology, we describe what we do as “making the diagnosis.” In a recent report the Institute of Medicine pointed out that the failure to make the right diagnosis is one of the leading causes of bad outcomes and high costs in health care. If you don’t get the diagnosis right, it is impossible to deliver the right therapy.

I would extend this further. The way I see it, it’s not just that we make the diagnosis, but by making a diagnosis we also make a treatment recommendation. Of course, it is up to the clinician to decide what is right for a particular patient, but we are setting the parameters by which the appropriate treatment gets done.

How is new technology affecting the role of a pathologist?

We’re not just peering into a microscope anymore. We are practicing precision medicine.

In today’s pathology lab, information systems increasingly guide the diagnostic process. We use powerful computers and sophisticated software, augmented by molecular techniques that enable the types of cells and tissues to be identified with greater accuracy. We use molecular tools not only to help us diagnose disease but also to tell the treating doctor what therapy is likely to work, based on the genes that have been mutated. The decisions pathologists make are critical in making sure that patients get the right therapy.

Does Yale Medicine’s Department of Pathology have any new capabilities that you find particularly exciting?

We now have a robust program in genetic sequencing of tumors. Using the technology that we have today, no two tumors I have ever seen are identical. There will always be some variation in how a tumor develops. The way that we guide therapy increasingly is by understanding that while there may be, say, four different tumor types by our usual diagnostic criteria—A, B, C and D—and we now know that even within each type, each tumor has a different pathway by which it has become a tumor. We can now see that there are more pathways; there is an A-1, an A-2 and an A-3.

We don’t always understand the implications, yet, but these subtle differences are increasingly turning out to be important. For instance, a new drug may appear for one of the pathways that can make a dramatic difference in outcome. This is the era that we are in.

Can you tell us about some of the pathology research that is under way at Yale Medicine?

Immunotherapy is another recent development. Along with a lot of other scientists, we are working on finding ways to predict which patients will respond to modern immune-activating therapies. So you might have two patients with tumors that appear to be identical and with similar markers, but they may respond very differently to immune therapy because the immune system is unique to each individual.

Every individual is different, and every person’s life story is different. All these factors come into play when cancer develops, and we are working to understand how and to find ways to apply this knowledge to the practice of medicine.