Learning pathology

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Author: Mikael Häggström [notes 1]

General notes edit

The goal of this resource is to make a new pathology trainee able to properly handle at least 80% of cases that are expected at an average general pathology department, including the exclusion of the most pertinent differential diagnoses thereof.

Using this resource

In this resource, it is recommended to read attentively until (and including) emergent pathology. For the rest, is recommended to scroll quickly through this resource to get an idea of its content (unless where something is marked as important to memorize), and then keeping it at a known location for whenever information is needed for a corresponding patient case. After all, other doctors and even laypersons can look up diseases and conditions themselves, including microscopic descriptions, without the need for a pathologist consultation, so the expertise of memorizing such readily available information is expendable. In a world where diseases and conditions can readily be looked up, a major skill that distinguishes a pathologist from any person with Internet access is mainly the ability to identify and put words to findings on microscopy or other non-written results, and to conceive most likely diagnoses based on both verbalizable and more abstract appearances. Another major skill is to be able to deal with unusual or equivocal presentations. Unusual or equivocal presentations of very common diseases and conditions are still generally more common than rare diseases, and constitutes a major workload in everyday pathology practice. However, most textbooks still give disproportionately large room for rare diseases compared to such presentations. Nevertheless, strive to master the common conditions (including the most common pitfalls) before diving into the uncommon.

What a pathologist needs to memorize

The best method for memorization is generally through repeated exposure in everyday practice, and the scope thereof will depend on your eventual location and subspecialty, and you will eventually forget everything else, more or less. Yet, the following things are most important for a pathologist trainee to focus on memorizing:

  • Emergent pathology, mostly relating to intraoperative or frozen section consultations. This includes information that usually cannot be timely looked up on the Internet when needed.
  • Main pitfalls: Most common and dangerous situations where a pathologist may not recognize the need to look something up further or ask a senior colleague.
  • Patterns and signs which can be seen grossly or under the microscope. It confers the ability to translate visuals into words that can be looked up if needed.
  • Knowledge of where to find information for various situations. It includes which person or which search engine is most useful for various clinical situations. See the Using resources section below for further information.
  • Proficiency in diagnosing equivocal or borderline cases where readily available sources and evidence usually deal with discrete and specific disease entities and subcategories thereof. 
  • Having an idea of one’s unknowns; being aware of unfamiliar fields. For example, a pathologist generally does not need in depth knowledge about cases that are generally sent out to specialized centers (such as pediatric musculoskeletal oncology), as long as that pathologist is aware of lack of knowledge in that field.
What you need to memorize.jpg
  • How to deal with Internet denialists and their exams. With the ease of access to pathology information on the Internet through smartphones and computers, those studying for the everyday practice as a pathologists should not spend time memorizing what can essentially always be conveniently and timely be looked up in times of need. This includes most of the content of books that are sorted by titles of diseases and conditions, because if the name of a disease is already known, then it can relatively quickly be looked up when needed. The topics listed above are already immense enough to cover a lifetime of learning. Nevertheless, the path to pathology certification includes one or more exams, whose questions are largely made up of people who act as if they were Internet denialists; as if they do not acknowledge the access to the Internet in everyday pathology practice. Therefore, this resource also includes a chapter on dealing with Internet denialists and their exams.

To test your knowledge on memorazation-worthy information, seek questions that present you with a possible real life situation, as well as all pertinent information you can readily look up or ask from fellow trainees before needing to answer the question, so to ensure that it tests you on pertinent information as per the items above.

Using resources

This resource is written with the intention to teach you what to do in various situations you are expected to encounter during your first years of pathology training, at least until the point that you are usually fairly confident about what disease or condition you have at hand, because then you know what words to use to look it up in the vast literature out there. At that point, the fastest way to get more information is generally by Googling the disease or condition name, followed by pathology outlines (which is generally the most likely to quickly give you the information you need). The most efficient method of studying to solve a case at hand is to not read articles in their entirety, but to scroll directly to the parts that are most likely to give you the information you need (generally past the first half of Pathology Outlines articles).

Specific search methods for some specific purposes include the following (and the author has no financial or other conflicts of interests in mentioning any of these):

  • Google, and then clicking the Images tab, if you just want to see more micrographs of the disease or condition. Even when you don't have a clue what condition you are looking at, you may find something that looks similar to your case by entering words you would use for the microscopic findings that you see.
  • Adding cancer.net staging in Google searches for definitions of cancer stages, for example Googling prostate cancer cancer.net staging. The first search will then generally be the one from the American Society of Clinical Oncology.
  • Considering a subscription for ImmunoQuery (or equivalent database if you find one) in order to generate the most pertinent immunohistochemistry stains when you have two or more differential diagnoses for a case at hand. It is not sufficient to just memorize a few usually positive or negative immunostains for each disease and condition, because what you need in reality is to figure out what immunostains to order so that you can pinpoint one diagnosis among your multiple differentials. To master that, you will need to memorize a vast amount of immunostains and at what percentages they are positive for a vast amount of diseases and conditions, or you can have an online service like ImmunoQuery do that work for you. After all, in pathology there is essentially no immunohistochemistry that is so emergent that you do not have the time to use a computer or smartphone to look it up.
  • ClinVar to look up the pathogenicity of specific genetic variants/mutations.

If the above resources do not provide a sufficient answer:

  • Googling what you are looking for. You may add the word pathology or equivalent if results are too clinical or layman-oriented. Before even reading the title of results, first look at the URL. If it is from a reputable organization then you may proceed to check if the title is pertinent to what you are looking for, but if it is from an unfamiliar site then you should only proceed if you don't find a better source among your search results, and you will need to look for additional proof of reliability such as authorship of the content in order to use it in the diagnostics of any case. You can generally rely on more articles for presumably well-established topics (such as anatomy, and relatively common diseases) than for potentially controversial and experimental topics, in which case you generally need to ask yourself if the author has a conflict of interest.

Ask a colleague at least whenever your own memory or a resource search is not enough, and there is a significant risk that you may do something irreversible that will negatively affect a patient.

Regarding lectures and knowledge your colleagues will tell you, make a judgment for each piece of information if it fits a criterion for memorization, or if it merits being written down somewhere you can find it so that you can look it up when needed.

Wikipedia often shows up among top Google results, and is generally accurate.[1]

Whenever possible, use textbooks that you can quickly access online (including in your personal cloud storage), because you will likely always be close to the Internet, but not always close to your textbook collection. Keep in mind that for the vast majority of content, you only need to have a hunch of where to find it again when needed, or what search terms to use.

Dealing with Internet denialists and their exams

An Internet denialist probably knows about the existence of the Internet, but keeps teaching as if it didn't exist. An Internet denialist generally does not seem to distinguish memorization-worthy from look-up information, finding pride or other justification for memorizing even facts that can presumably always be looked up in time of need, and often even practically useless information. The main problem is that when Internet denialist has memorized something, he or she often assumes that pathology trainees should memorize it as well, and will waste time and effort from the pathology trainee on such memorization. In reality, when something is encountered and looked up something enough times, it will generally get memorized, and apart from the necessary items listed in the previous sections, it is generally more efficient to let time tell which situations will be common versus uncommon, rather than trying to memorize knowledge that may never be needed.

Yet, as a trainee, the best approach is to never call a senior an Internet denialist, even in gossip, out of respect and professionalism. Also, generally do not defy Internet denialist study instructions from seniors, even if they seem like a relative waste of time, but possibly politely question if it is necessary. Yet, you may spend the minimal time and effort on such tasks in order to spend more time with your patients at hand, or learn things that are necessary to memorize. Don't be ashamed to say that you don't know the answer when an Internet denialist puts you on the spot about a piece of look-up information, and don't be ashamed to say that you usually look it up when a clinician asks about look-up information. Also, while you should initially focus on learning the most common conditions, seniors may already have learned the common conditions, at least in their field of interest, and they will often distract you from your pursuit by presenting rare conditions to you, because that is now interesting to them, but do not spend more than minimal time or mental effort on such rare conditions during at least your first years. Yet, you may still pretend to be interested and thereby encourage their enthusiasm.

Accordingly, the final aim of this resource is to help pathology trainees to give accurate and clinically useful reports to clinicians, in synergy with the resources that are available in everyday pathology practice, and to establish routines to continue such practices. The intended end result is to help clinicians to improve the lives as much as possible to as many people as possible, even if it means forgoing the prestige of becoming a walking encyclopedia.

An Internet denialist exam is basically any exam wherein the examiner does not have access to the Internet, and typically is not allowed to ask colleagues either, and does not get such pertinent information presented, even for non-emergent topics that can conveniently and timely be handled by such resources. Since the Internet and teamwork are fundamental parts of everyday practice, such exams are thereby of a different dimension compared to reality, and their score do not correspond to actual pathology proficiency.

Exam studying

Efficient studying for Internet denialist exams will allow you more time, effort and brain space to memorize what you actually need, as well as to perform for example studying for solving your actual everyday pathology cases as per sections above. Since exams and everyday practice are generally very different, it is more efficient to study either specifically for an exam, or to study specifically for solving each case you encounter in everyday practice, rather than trying to study any material with the intention of covering both purposes. After all, you will become proficient at what you do: If you read textbooks from front to back then you will be more proficient at reading textbooks from front to back, and if you study to solve everyday cases on your table then you will become good at that, whereas the best way of becoming more proficient at multiple choice exams like the American boards is to practice qbanks with a similar multiple choice format. There are multiple ones for the American boards (PathPrimer, PathDojo, BoardVitals, ASCP Resident Q bank), and you should preferably go through all of them and then repeat at least the questions you failed the first time, before continuing with any other types of study materials. People differ in their opinions of what are the best qbanks, so form your own opinion which you think works best for you during the first round, and preferentially repeat those. For highest yield, don't read every explanation for every answer, but just the answers that contradicted your belief, just enough to learn why it wasn't what you initially thought. Also, you don't have to memorize every clue and every detail of the right answer, but rather get a hunch of what makes the right choice most likely, because that's basically all you need to choose that right answer if it would appear in the actual exam. For example, for a picture of a hairy cell and a question about mutations, your brain probably just needs to associate it with for example "barf 600 something", rather than knowing that suspected hairy cell leukemia is confirmed by genetic testing for the BRAF V600E mutation (and in everyday practice this can timely and conveniently be looked up when you need it). To check if you have remembered a question sufficiently, you may for example review the correct answers for a test until you almost immediately find them to be reasonable rather than unfamiliar, and repeat the question later if you have the time. If the Qbank shows the average percentage of test takers who got a question right, put somewhat less effort on questions with very low percentage, since you generally have less of an expectation of knowing those. By practice, your mind will in time be primed to select the most likely answer according to the epidemiology in the population you practice on, and when comparing to the real life population, the typical imaginary population in exams has for example a much higher rate of serious disease (particularly cancer) rather than benign, unspecific or artefactual findings. The exam population also has a vast overrepresentation of very rare diseases that happen to be related to certain (but still not directly clinically useful) molecular processes. For example, an exam patient with bleeding diathesis has a relatively high probability of having for example Bernard–Soulier syndrome because it is related to a receptor of the clotting cascade. After you are done with the exam, you need to more or less re-prime yourself back to the real population where for example idiopathic thrombocytopenia is far more common. Also, in multiple choice exams, a statement that a disease would never have a certain feature can generally be regarded as false, since even exam makers cannot exclude that such a feature may at some point occur somewhere in the world.

Teaching pathology

Strive to always begin with the real life situation in which the point you want to teach is relevant for improving the management of a patient. If you can't think of a situation where something would relevant, generally don't teach it.


  1. For a full list of contributors, see article history. Creators of images are attributed at the image description pages, seen by clicking on the images. See Patholines:Authorship for details.

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  1. Kräenbring, Jona; Monzon Penza, Tika; Gutmann, Joanna; Muehlich, Susanne; Zolk, Oliver; Wojnowski, Leszek; Maas, Renke; Engelhardt, Stefan; et al. (September 24, 2014). "Accuracy and Completeness of Drug Information in Wikipedia: A Comparison with Standard Textbooks of Pharmacology ". PLOS ONE 9 (9): e106930. doi:10.1371/journal.pone.0106930. PMID 25250889. Bibcode2014PLoSO...9j6930K.