I got this really great question from one of my students, and it got me thinking about how important it is to have really clear definitions of pathologic conditions. These three conditions – aneurysm, thrombosis, and stenosis – are totally different things. And yet they can sometimes co-occur, or one can cause another – so it can become confusing! I thought I’d share the question and my answer here, because I’m sure there are other students who are having trouble understanding these disorders. Here’s the question: I was reviewing the Blood Vessel Pathology lecture notes from this past week an ..read more

Q: Would a pyknotic cell be a form of necrosis or apoptosis? Or am I totally off base here? A. No you’re totally not off base – that’s a really good question!! We typically use the word “pyknosis” to mean one of the three nuclear patterns seen in necrotic cells…but pyknosis can also occur in apoptosis! I’ll explain a bit more. When cells undergo necrosis, they show a lot of different morphologic abnormalities. Overall, necrotic cells appear enlarged and more eosinophilic, and their nuclei look abnormal due to breakdown of DNA. There are three specific patterns of nuclear change in n ..read more

If you want to be precise, the word pathology means “the study (logos) of pain (pathos).” And it’s true, in a way, because a lot of the things we discuss in pathology involve some sort of pain. Not to mention the pain of studying pathology itself, but we won’t get into that, since this is a pain-free space. What we really study in pathology isn’t pain, exactly, but disease. So if you’re starting out in a pathology course – or even if you’re halfway through – it’s not a bad idea to come up with a little plan of attack for studying diseases. Why use a plan when learning new diseases? Becau ..read more

Here is a great question I got from a student about the genetics of Factor V Leiden. Q. Factor V Leiden is autosomal dominant – but it doesn’t seem to follow Mendel’s laws. Would you say it shows incomplete dominance? A. This is such a good question! Factor V Leiden is an autosomal dominant disease – and you’re right: it does NOT follow Mendelian laws. However, the non-Mendelian pattern it follows is not incomplete dominance, but incomplete penetrance. First, here’s why Factor V Leiden is a non-Mendelian disorder. Factor V Leiden is an autosomal dominant disease. If it followed Mendel’s laws ..read more

Do you know what a “storiform” pattern is? Yeah, neither did I when I was a medical student. However, that term did get thrown around in pathology lectures a lot, without any description or definition. There are lots of terms like this – so I’m gonna just go ahead and create a new category called Words Pathologists Use In Lecture As If You Know What They Mean.  I think it’s important to pause and define these terms, because otherwise this is what happens: given the sheer volume of stuff you’re supposed to learn, and the minimal amount of time you have to accomplish this task, you’re not ..read more

There are two types of gallstones: cholesterol stones and pigment stones. If you didn’t know anything about gallstones, you’d guess (rightly so) that cholesterol stones are made up of cholesterol. And you’d also probably guess that you get cholesterol stones when there’s too much cholesterol around. But how, exactly? And pigment stones – what are those made of? Pigment? Turns out there are very good explanations for all of these questions. Let’s take a look. Cholesterol gallstones Cholesterol gallstones contain – not surprisingly ..read more

Can you identify this organism? Wow, I got lots of good feedback on the last post I did with a “name that bug” theme – so I’m going to do more! I like learning this way – especially when there’s no one around to judge you. Unknown conferences during pathology residency could be pretty brutal…but we’re all friends here – so if you don’t get the answer right, it’s not a problem – it’s just an opportunity to learn something new. How nice. Okay. Start by taking a look at this image – maybe you’ll know right away what it is, and may ..read more

Can you identify this organism? Start by taking a look at the image – and if you need more hints (it’s okay if you do!), keep reading. The answer is at the bottom – so don’t scroll down until you’re ready.   How do you get it? Let’s start by talking about the places you’re most likely to encounter our mystery organism. This little guy likes to hang out in contaminated dust or soil. The most common means of contamination is through bird or bat droppings (yuck). The organism is acquired by inhalation – so spelunkers (who might br ..read more