• Jena Martin MD

The pepperoni

It's late in the frozen section lab and things are getting goofy.

The frozen section lab is located next to hospital operating rooms. It's where we pathologists evaluate the tissues and organs surgeons remove and tell them what to do next. (The surgeons might tell you it's they who are telling us what to do, but we know better. 😉) They send us the tissue they've painstakingly removed from you (the patient), and we tell them what the problem is and if they need to take more. It's called the frozen section lab because the tissues are frozen. Freezing makes the tissues hard enough to cut in 4 micron thick slices, place on a slide and then examine under the microscope.

We're there at 9:30 pm because we're all waiting on a late case. There's me (the pathology resident), the histology technician who will freeze and cut the case, and the consultant - the head pathologist for the shift. The surgeon working so late is well known to us all. That's because he's usually late. He removes about 4 prostates every day he operates and the last one usually goes late. Because of how we do things in this hospital, we need to evaluate his prostatectomy case immediately after it is removed. We are waiting for the buzzer from his Operating Room to ding, at which moment I will go down the empty OR halls to collect the tennis ball-sized gland from his surgical nurse.

In the meantime though, we are waiting. And the consultant on duty is fun. He's the sort of pathologist I can ask dumb questions of. He's newly graduated from this program and also very mellow. He has bought us a pizza because we are here so late. (No other consultant does this). For all these reasons, he's so unusual that I feel sort of giddy working with him. The atmosphere is ...fun. Very atypical.

He knows his mentor is also working late across the street, so he makes a funny suggestion. "Let's trick Tom with a piece of pepperoni. " We giggle conspiratorially, and take a greasy pepperoni from the pizza left in the break room. The histology technician, the tobacco-scented, nearly skeletal wife of a long distance trucker gives us a look of raw skepticism. But nevertheless she freezes it, cuts a piece, stains it and sets it down on a slide for us to look at under the microscope. Per protocol.

When we see it under the microscope, it looks dark. Full of odd, rectangular shapes, all variable muscle fibers. The consultants turns on his microscope camera and opens it for our interdepartmental tele-pathology channel. Then he calls up Tom.

Hey can you open your telepathology channel and take a look at this testicular tumor with me? (Good organ choice, I think, as almost anything can grow in a testes. Or ovary. The primordial soup of sperm and egg can produce all sorts of weird-looking tumors. Makes this muscular garbage seem like a plausible tumor.)

We can barely stop from laughing as we hear silence from Tom over the speaker phone. He stalls. He asks the questions we ask in pathology - How old is the patient? What are the hormone levels in the blood? What did it look like when you cut into it? - Then, silence. "Where did you say it was from again?" Things were not adding up for Tom, and it looked like he might figure it out on his own, but I blow the whole prank as I snort in the background of the call. "Ding ding ding", rings from the O.R.. And I'm off to fetch the prostate.

Pathology is a two-part process. First, observe. Second, diagnose. That may be overly simplified, but it gives the general framework. It helps because sometimes in pathology we review the wrong tissue. Maybe it got mixed up from the wrong case. Maybe it is part of a study set meant to confuse pathology residents, like dog skin tumors. Or it could even be a piece of pepperoni. We have to remain present in the observational phase before rushing to a diagnosis. How can we remain skeptical of what we are seeing, skeptical enough that we maintain an open mind and see things for what they are?

When, might I ask, is something a pepperoni? Or, as Carl Sagan put it, baloney?

One of modern science's greatest communicators, astronomer Carl Sagan, provided a handy guide to overcoming bias when evaluating the world. He called it, marvelously, the Baloney Detection Kit.

Before we unpack his Kit, let's zoom out for a minute, beyond the pepperoni and the prostate, beyond the individual and specific personal decisions. Given the state of discourse in our world, we all could use this Kit. In fact, part of what drove me to write about pathology in this blog is a crisis. A crisis in science. A crisis in medicine. It makes itself shown in discussions about vaccines. Or when people talk about using homeopathic medicine. It is a crisis created from a lack of trust. Many people don't trust modern medical institutions.*

How do we know something when we can't trust authority or institutions? These institutions - universities and scientific experts - are the source of most knowledge. We assume that it's reliable facts and knowledge that lead to trust, but perhaps it's the other way around - we first have the trust in the source and then we believe their knowledge. This goes against one of my intents in writing about pathology - I wanted to show you the proof, the physical, tangible proof of disease and how we see it. (Back to the granular focus again.)

But to increase trust it turns out that I also need to show you how we arrive at these diagnoses, how we mediate the truth of biology and of your body. And how we do that is part of the legacy of scientific thought. You don't have to be in the lab to have an informed, skeptical mind. In fact to navigate the current flood of information about health and wellness you need to have better mental hygiene. The scientific approach offers a way to analyze the world and discover what's true, as long as you first tune up your mind.

And that's where Carl Sagan comes in.

Carl Sagan was an astronomer and physicist. He looked up and out with a telescope. I'm a pathologist. I look down and into tissues with a microscope. Superficially we seem kind of opposite. But that difference ignores what lies under our approach; like Carl Sagan I use the scientific method to learn from and analyze information.

There's a lot to aspire to in the work of Carl Sagan. He, of the original Cosmos fame, easily conveyed wonder and curiosity about the complexities of science. He advocated for the scientific method and skepticism, which under-girded his efforts to help people understand science. Although he died in 1996, his elegant "Baloney Detection Kit " gives us some guidance yet today.

"In the course of their training, scientists are equipped with a baloney detection kit. The kit is brought out as a matter of course whenever new ideas are offered for consideration. If the new idea survives examination by the tools in our kit, we grant it warm, although tentative, acceptance. If you’re so inclined, if you don’t want to buy baloney even when it’s reassuring to do so, there are precautions that can be taken; there’s a tried-and-true, consumer-tested method.

I've included his entire Detection Kit at the end of this post. (Spoiler: It's not an actual kit. It's a set of 'rules of thumb' for you to follow.) Although I wasn't explicitly taught using these principles, these precepts were embedded in my medical education and pathology residency, and guide how I observe and diagnose disease in my daily work life as a pathologist. Three of his rules are the most immediately relevant to my work, and may also enlighten your approach to fact-gathering. (You can skip to the end to just read his Baloney Detection Kit (entire article linked here).)


Encourage substantive debate on the evidence by knowledgeable proponents of all points of view.

I subspecialize in dermatopathology. That means I know more about skin conditions than a pathologist who is an expert in liver pathology. And, there are also skin problems that are beyond my scope of practice. It's humbling, but when I'm struggling with a case, the best thing to do is share it with my colleagues. It's not always easy to lay aside your pride and say you don't know what something is, but it is normal. I might not be seeing the evidence that is before me the same way my colleague can. I may not have the same set of stored information they do when they see the slide. Just talking over our impressions is a great way to reconsider a case. And this is true for most medical specialties - physicians work best talking to other doctors to help coordinate the care of a patient and solve complex problems.

Sadly I think it is really rare in modern workplaces to be able to voice your problems in order to seek solutions. Are you encouraged to generate uncertainties and debate them in your work? Just think about it for a minute - modern science is built on the idea that you cannot figure out your problems alone. You are not expected to. And, importantly, you are also not expected to always be right.


Spin more than one hypothesis. If there’s something to be explained, think of all the different ways in which it could be explained. Then think of tests by which you might systematically disprove each of the alternatives.

Do you like checklists? It would be an understatement to say that I do, for life and for work. But in my job I don't just list out what I need to do; I write up all the possible explanations, which then generates my to-do list. The list I create when working on a case is called the Differential Diagnosis.

To distinguish between/differentiate among diagnoses with shared features, we create lists. The list makes order out of chaos because it is informed and relevant. An appropriate list of diagnoses allows you to effectively order tests to prove and disprove the possibilities. This is the power of the differential diagnosis. It provides a framework to approach the question (what is this?) that is focused and not scattershot. Good training helps you develop long differential diagnoses lists that you can implement without too much overthinking. Rather than becoming excellent at detecting each disease perfectly, you are better served to develop effective lists of possibilities.


Try not to get overly attached to a hypothesis just because it’s yours. It’s only a way-station in the pursuit of knowledge. Ask yourself why you like the idea. Compare it fairly with the alternatives. See if you can find reasons for rejecting it. If you don’t, others will.

Being right is admittedly one of my favorite feelings. Maybe that's why is it so difficult to not get so attached to my ideas. It feels like I must actually mourn my initial impressions and plans. I treasure them, mulling over the implications of how I am right. And then, because I have learned from experience and because I think at heart I am curious, I open myself up to another idea. No matter how neat or exciting my explanation might be, I have to be able to accept the information I am gathering from my reality.

I associate this rule of thumb with another medical maxim: If you hear hoof beats, don't think of a zebra. This is a way of explaining Occam's Razor, another of Sagan's tools. Occam's Razor: the simplest and most common explanation is most likely to be true. In medicine in general, we have to consider the most exotic explanation (zebra) so that we don't miss the rare appearance. And zebras are eye catching; our mind is drawn to this sort of exciting explanation. We can get attached to this unique answer, and feel special in the light it casts: "I thought of the zebra!". It's important to not forget that horses are the most likely cause of hoof beats.

These are my three highlights of the Baloney Detection Kit aka the scientific method, in action behind the microscope. Can you think of examples from the problems you face, and decisions you make? If we all tried to prove ourselves wrong more often, our society might be in a better place. And no one would fall for the pepperoni. Or the baloney.

Carl Sagan's Baloney Detection Kit.

  • Wherever possible there must be independent confirmation of the “facts.”

  • Encourage substantive debate on the evidence by knowledgeable proponents of all points of view.

  • Arguments from authority carry little weight—“authorities” have made mistakes in the past. They will do so again in the future. Perhaps a better way to say it is that in science there are no authorities; at most, there are experts.

  • Spin more than one hypothesis. If there’s something to be explained, think of all the different ways in which it could be explained. Then think of tests by which you might systematically disprove each of the alternatives. What survives, the hypothesis that resists disproof in this Darwinian selection among “multiple working hypotheses,” has a much better chance of being the right answer than if you had simply run with the first idea that caught your fancy.

  • Try not to get overly attached to a hypothesis just because it’s yours. It’s only a way-station in the pursuit of knowledge. Ask yourself why you like the idea. Compare it fairly with the alternatives. See if you can find reasons for rejecting it. If you don’t, others will.

  • Quantify. If whatever it is you’re explaining has some measure, some numerical quantity attached to it, you’ll be much better able to discriminate among competing hypotheses. What is vague and qualitative is open to many explanations. Of course there are truths to be sought in the many qualitative issues we are obliged to confront, but finding them is more challenging.

  • If there’s a chain of argument, every link in the chain must work (including the premise)—not just most of them.

  • Occam’s Razor. This convenient rule-of-thumb urges us when faced with two hypotheses that explain the data equally well to choose the simpler.

  • Always ask whether the hypothesis can be, at least in principle, falsified. Propositions that are untestable, unfalsifiable are not worth much. Consider the grand idea that our Universe and everything in it is just an elementary particle—an electron, say—in a much bigger Cosmos. But if we can never acquire information from outside our Universe, is not the idea incapable of disproof? You must be able to check assertions out.

  • Inveterate skeptics must be given the chance to follow your reasoning, to duplicate your experiments and see if they get the same result.


*I can't better elaborate on the well founded basis for this lack of trust than the amazing Dr. Vinay Prasad, whom I encourage you to follow on Twitter! He blows apart the myths and sloppy work propagated by journalists, science writers and doctors. He analyzes the work and the authors of medical research - what conclusions they draw, how they are paid (yes, rank corruption underlies a lot of medical research), and how they frame their results to make their case. It's sobering, challenging and insightful. He will give you the terms you need to dismantle the false claims of modern medicine.