Pathologist using a microscope while conducting diagnostic testing in a laboratory

The Life-Changing Doctors You Never Meet

June 28, 2024

A patient visits the doctor’s office for a blood draw, urine culture, or biopsy. The doctor sends out a sample to a lab for testing. The test results could show something minor, like a cold, or something more serious, like a life-threatening tumor. Patients typically hear the results from their physician, who likely consulted with experts in the lab whom the patient will never meet: pathologists.

Dan Green, MD, and Stephen Lagana, MD, are expert pathologists at Columbia in the Department of Pathology and Cell Biology. They sat down with us to explain their jobs, describe their training, and share the most fascinating cases of their careers.

What is Pathology?

The dictionary defines pathology as the “study of the essential nature of diseases,” but Dr. Green puts it this way:

“Anytime anything is removed from a patient’s body—like a blood sample, piece of tissue, or fluid from a cyst—it’s going to a pathologist in a laboratory for analysis and testing that leads to a diagnosis.”

The Two Types of Pathology

Pathology is organized into two camps based on the sample studied. One camp is “anatomical pathology,” which is the analysis and diagnosis of tissues. For example, anatomical pathologists examine a skin sample after a biopsy or a tumor that is removed during surgery.

“We might be able to say how invasive the tumor is, how aggressive it’s likely to be, or if it’s entered blood vessels or lymph nodes,” says Dr. Lagana, a surgical pathologist.

Anatomic pathology also examines certain cells in fluids (like fluid removed from a cyst) and performs autopsies. Over the years, this field has become more predictive, providing a diagnosis, stage, and information on how a patient may respond to certain drug therapies. 

The other camp is “laboratory medicine,” also called “clinical pathology,” which tests everything that doesn’t fit into anatomical pathology, like blood and urine samples.

Clinical pathology includes many areas, such as clinical chemistry (like checking blood for potassium levels), clinical microbiology (like testing sputum for pneumonia), blood banking and transfusion medicine, and molecular pathology (which includes genetic testing for inherited diseases). A clinical pathologist uses a range of tools, from a basic petri dish to sophisticated mass spectrometry, to identify bacteria.

Training to Become a Pathologist

Every pathologist is a medical doctor who went to medical school. They then do a three-year residency if they want to practice either anatomic pathology or clinical pathology, or a four-year residency if they want to practice both. In addition, most pathologists go on to do one or two years of fellowship training to specialize in a particular area, such as gastrointestinal pathology or infectious disease testing.

The Best Part of a Pathologist’s Job

“It’s really satisfying to get a tough, unusual tumor and figure out what it is,” says Dr. Lagana. “At Columbia, we get some of the most unusual cases, so I’ve seen a lot. Whenever a patient’s case crosses my desk, I know there’s a really good chance I can give them the right answer. I take a lot of pride in that.”

Dr. Lagana remembers challenging cases from Columbia’s Celiac Disease Center that he investigated years ago. The patients had celiac symptoms, but their lab test results were different from those of usual celiac patients. Dr. Lagana read a study that found similar patients had reacted to a specific drug, and that discontinuing the drug resolved the symptoms.

“Since then, I’ve seen cases that look like the worst celiac disease you’ve ever seen, but if I find that medication in their chart, I call the gastroenterologist and say, ‘If this patient’s blood tests are negative for celiac, they’re probably suffering from a medication reaction.’ I love to make that diagnosis because patients are cured within days.”

For his part, Dr. Green, a clinical microbiologist, is interested in rare pathogens that may only be encountered once in a career, which was the case with COVID-19. 

“I think everyone here remembers early 2020 and putting everything we had on the line,” he says. “When we were first doing patient testing, and our positivity rate was 50 percent—which I’d never seen so high for a respiratory virus—I thought our test wasn’t working. Then we realized the results were accurate, and that’s just how much COVID was happening. Those moments of knowing something before the rest of the world were interesting. I think everybody here is extremely proud of what we were able to do.”

Clinical pathology also involves identifying critical connections others may miss. For example, Dr. Green might see a blood culture growing an unusual bacterium, and he knows that bacterium—in addition to causing infection—puts a patient at higher risk for colon cancer.

“If you send a test to a commercial lab, they’re just going to report the name of the organism and stop there,” Dr. Green says. “But our lab is connected to our providers and patients, so when we see a result like that, we recommend the patient gets screened for colon cancer. Making that connection to improve patient care is extremely gratifying.”

Patient Safety in the Lab

Dr. Green explains that laboratories are highly regulated at the state and national levels, and a long list of guidelines and systems are in place to monitor quality metrics, certify the competency of technicians, and safeguard other quality measures. Electronic records also help ensure laboratory safety and patient protection by confirming that the patient’s identity and tests ordered are always accurate.  

“Quality is the backbone of what clinical laboratories do,” says Dr. Green. “A mistake can cost someone their life, so everything has to be exactly right for patients.”

What’s Next in Pathology

For decades, anatomic pathology has been refining the diagnosis of cancer. What started as simply “cancer” became “carcinoma” versus “lymphoma,” and it continues to get more specific. Increasing that precision could convey information about how a tumor behaves.

“There’s a lot of hope that AI can further refine that granularity so we can say, for example, how likely a patient is to respond to immunotherapy. There’s a lot of research being done in that area,” says Dr. Lagana. 

Technology has been widely adopted in clinical pathology to help automate testing. For example, identifying bacteria that used to require 24 hours of growth on a plate has been sped up to 20 minutes through the use of mass spectrometry. Other systems called “total lab automation” are also becoming more common.

“When laboratories implement these systems, they automate the manual work, which lets the technologists focus on the more intellectual part of their jobs,” says Dr. Green. “It’s good for our teams, and it shortens patient turnaround times, which greatly impacts care.”

Pathologists are integral to the cycle of care a patient receives. While patients only know them as a name on a lab report, these highly skilled medical doctors are essential to ensuring accurate diagnosis and treatment.