1

SUGGESTIONS FOR STUDYING PATHOLOGY IN THE MB BS CURRICULUM, UNIVERSITY OF ADELAIDE Dr A. Barbour, Discipline of Anatomy and Pathology, February 2011. Why is understanding pathology and the scientific basis of medicine important? Doctors treat and aim to prevent disease. They thus need to understand disease. They also need to understand the structure and function of the human body (e.g. anatomy, histology physiology, genetics, biochemistry) as it is an alteration of the normal processes that lead to disease. Pathology is the study of disease. It links the basic medical sciences such as anatomy, histology, biochemistry and physiology with the clinical knowledge required for medical practice. If you understand the pathology of a disease you understand its predisposing factors and causes (aetiology), the mechanisms by which these lead to disease (pathogenesis), the structural (morphology – including macroscopic, microscopic and ultrastructural) and other changes that the disease causes in the body, the functional consequences of these changes, or how they manifest as symptoms and signs and on investigations, as well as the course of the disease including potential complications and outcomes. Pathology is involved in patient management. The terminology used in pathology forms the basis of medical terminology. Pathology is also a medical specialty (with several different areas: Haematology, Immunology, Chemical Pathology, Anatomical Pathology, Forensic Pathology, Microbiology and Genetics) and you need an understanding of pathology to be able to communicate with pathologists about your patient, understand their reports and take appropriate action. Pathology also has a broader application as it has played, and will continue to do so, a vital role in the development of new treatments and methods to prevent disease. Also note that many medical specialists e.g. surgeons and radiologists need a comprehensive understanding of pathology, and in some cases histology and histopathology (e.g. opthalmologists, dermatologists, renal physicians) and pathology forms a component of their specialist training. An understanding of pathology is necessary for

• the interpretation of clinical symptoms and signs • the formation of appropriate differential diagnoses • choosing appropriate investigations • the correct interpretation and understanding of investigation results, including radiological • refining differential diagnoses to arrive at a definitive diagnosis • choosing appropriate treatments and management strategies and understanding how they work • communication with patient and colleagues • the provision of prognostic information • monitoring treatment/progress • instituting preventative measures at patient and population levels • understanding medical and research publications • understanding clinical and scientific presentations • writing accurate and clear medical notes • as a foundation for postgraduate training • as a foundation for future research

Pathology is thus a central part of medicine and it is important for you to have a sound understanding of this discipline for competent medical practice. To fully understand pathology you need to have a sound knowledge and understanding of basic anatomy, embryology, histology, physiology, genetics, biochemistry, immunology, microbiology etc. It is important for you to learn the principles of the scientific basis of medicine, not just selected facts relevant to certain diseases. The latter approach leads to patchy knowledge, lack of understanding and inability to apply knowledge in different situations to which it was learnt i.e. problem solve. Memorising facts in the context of certain diseases will not result in the development of a solid foundation of knowledge and understanding necessary for your future career. Pathology is introduced in first year and there are increasing amounts in 2nd and 3rd year. Understanding 2nd and 3rd year pathology requires an understanding of the basic pathological processes covered in 1st and 2nd year. Some students find pathology difficult and don’t appreciate its significance, especially the morphological (macroscopic and histopathologic) aspects, thus don’t spend as much time learning it as they should. Understanding the morphological features of disease not only aids understanding of pathology but is also important for understanding radiology, surgery, pathology reports and the pathology presented in clinical meetings, conferences, journals etc etc. Likewise histology is not viewed favourably by many students but it is not only important for understanding how the body is structured and functions but as a basis for understanding pathology and its terminology and thus the diseases of your patients. Neglecting to learn pathology (and histology) thoroughly is thus likely to significantly disadvantage you later. While there currently is not much pathology in years 4-6, it is important that you continue learning pathology as it underpins your understanding of medical practice. There is a great deal to understand, and although pathology will be incorporated in CBL tutorials, lectures and resource sessions, there are a number of other resources we recommend to help you in developing a good understanding of pathology. Pathology resources include (see Resources in Pathology document for more information). • Lectures and lecture notes • Textbooks, including histopathology atlas, and associated websites • Pathology museum and catalogues, including Introduction, How to Use this Catalogue and Basic Approach to Interpretation and

Description of Pathology Specimens and Core and Classic Disease Processes sections • Freely accessible pathology related websites • Resources on Discipline of Anatomy and Pathology teaching resources website

2

General Understanding pathology is difficult without a background understanding of normal anatomy, physiology and histology etc so learn these first. It is important also that you understand relevant terminology e.g. tunica media, lamina propria, villous. Make sure when you look at anatomical specimens, that you don’t just memorise specific features but develop an overall appreciation of them in 3 dimensions, be able to orientate them and also appreciate some of the detail e.g. that the lungs have a fine spongy texture and numerous hollow structures running though them, noting their size and the different features of their walls (e.g. to distinguish pulmonary arteries from bronchi). The liver also has numerous hollow structures running through it but looks quite different. Look at relative shapes, colours, consistencies, and look at features in relationship to surrounding structures. Notice features that may help you to orientate a specimen e.g. the structure and relationship of the different chambers of the heart (particularly ventricles), the features that distinguish the midbrain, pons and medulla, and which features are anterior and posterior or lateral and medial, so you can orientate a specimen. With histology don’t just learn specific features in micrographs but learn how to recognise them and to understand their relationships and how they all fit together, Understanding abnormal morphology (abnormal macroscopic and histopathologic appearances) and systems pathology are difficult without a background understanding of relevant basic pathological processes. Most diseases involve one or more of the basic or general pathologic processes i.e. cell injury or necrosis, cellular adaptive responses (hyperplasia, hypertrophy, atrophy, metaplasia), inflammation, healing, haemodynamic disorders including ischaemia, infarction, thrombosis, embolism, oedema and shock, neoplasia, and the principles of infection, immunology and genetics (covered in the early chapters in pathology textbooks). Thus to understand the pathology of a specific disease, you need a background understanding of these basic pathological processes. Once you have learnt about acute inflammation, the principles and visual features are often similar (although there are variations) whether it be e.g. in the lung, appendix or an infected skin wound. Having a sound basic knowledge and understanding of the scientific basis of medicine and a logical approach is important for problem solving in medicine. One can’t solve a complex case on the basis of patchy memorized information. Depth and breadth of learning are important, not just what you think will come up in exams and not just of common conditions. Learn things in a structured way rather than just random lists, as you are less likely to forget important things e.g. • Learn the factors that predispose to thrombosis in the context of Virchow’s triad. In this way you are less likely to forget any when

considering the predisposing factors for the deep venous thrombosis and pulmonary embolism in the 20 year old patient in front of you that are likely to be important to prevent it happening again (or in a family member).

• Learn the causes of anaemia in the setting of an overall classification, rather than just a memorized random list • Learn the causes of mechanical bowel obstruction under the classification: extramural, intramural, luminal The surgical/pathological/diagnostic sieve is a tool for formulating differential diagnoses, whether in clinical situations or for looking at pathology pots, especially when the diagnosis is not obvious. The categories include congenital, genetic, traumatic, inflammatory (infection and immunological), vascular, degenerative, environmental, endocrine, metabolic, nutritional, neoplastic, psychiatric, iatrogenic and idiopathic. A number of mnemonics exist for helping to remember the categories. One is: TIN CAN BED PAN. This is short for: Trauma, Inflammatory, Neoplastic, Congenital, Arteriovenous, Neurological, Blood, Endocrine, Drugs, Psychogenic, Allergic, Not known. You will need to spend more time on learning topics you feel less comfortable with/find more difficult. Week by week during the semester Many of you will find that you have to approach learning differently to the way you did at school. Most learning is self-directed, even in traditional lecture based medical courses. Lectures and other teaching sessions are there to guide your learning, with emphasis of important points and explanations of difficult concepts, but the learning itself is an active process that requires significant personal input outside of scheduled teaching sessions. It is important to be organised. Prepare a timetable for study. Set aside time each week to read about and take notes on relevant anatomy, histology, pathology, microbiology etc and lecture content, to look at relevant online resources and to go to the pathology museum. Also make sure you are aware of important deadlines e.g. when assignments are due. Raise pathology (and SBM disciplines) as learning issues in CBL tutorials. Lectures: review lecture content shortly after the lecture. Read and note relevant sections of a textbook in association with lecture notes to add to your understanding. Some lectures may contain a lot of detail but try to identify, summarise, understand and learn important points. Pathology lecture notes on the Discipline of Anatomy and Pathology resources web page may have useful information in addition to notes provided by the lecturer and often contain certain mechanisms that may not be clear in the textbooks. You will gain much more from resource sessions if you have prepared beforehand (textbooks, relevant lecture content, pathology museum, histopathology atlas and online resources). Resource sessions are not ‘teaching’ sessions but opportunities for you to think about and apply knowledge that you have gained from prior preparation and an opportunity to ask questions if you don’t understand something. Much of the pathology in resource sessions will have been covered in a preceding lecture, including discussion of macroscopic and histopathologic features. Review the theory and features before the resource session. Go to the pathology museum to look at the specimens beforehand. Textbooks give classic descriptions of morphologic features, but not all examples of disease will have all the typical features. Don’t only look at the specimens from resource sessions (more examples can be found via the index in museum catalogues). Look at images from other

3

sources (textbooks, websites). Don’t expect to be ‘taught’ to identify all macroscopic and histopathologic features. You will be given information in lectures on how to identify certain features, but you need to spend time practising yourself. Morphologic (macroscopic and histologic) features should not be ’memorized’ – learn to understand why the abnormalities appear as they do. Read the introductory chapters in the museum catalogues (Basic Approach to Interpretation and Description of Specimens, Core and Classic Disease Processes) Review information in resource notes (including diagnoses and the information they give). Try to answer the questions (though its not vital to answer them all) – relevant information may be found in lecture notes, textbooks, pathology museum catalogues etc. Resource sessions provide an opportunity to ask questions on identifying macroscopic and histopathologic features, and on other aspects of pathology that you are not sure of. Active reading and note taking When you read a textbook or information from another source, ensure that you think about and understand what you are reading and relate it to your existing knowledge in that and other areas. Think about how the pathology integrates with for example, the anatomy and clinical aspects (e.g. the specific coronary artery that is occluded to cause an MI affects the location of the infarct (anatomy), the changes on the ECG (physiology, clinical/investigation) and the potential complications (pathology). Understanding how a coronary artery becomes occluded (knowledge of normal coagulation (physiology) and of atherosclerosis and thrombosis (pathology)) is important in prevention (of atherosclerosis and thrombosis) and treatment of infarction (development of thrombolytic agents - pharmacology). Many medications act on the cytokines or mediators involved in pathological processes (pathology) so it is important to understand some of them and their effects so that you understand how the medications work (pharmacology.) Make sure that you understand terminology (look it up if you need to). Take notes that complement and add to CBL and resource session and lecture content. This may include summaries of important mechanisms or concepts or organised lists of risk factors or complications. Don’t note the majority of the textbook chapter, but add extra information and detail where appropriate to lecture and other notes to add to your understanding such that you have a concise, organised and reasonably detailed set of notes to learn from later for exams. Use lecture and resource session content (and content from other resources provided) as a guide as to what depth and breadth of knowledge you should learn. You then won’t need to go back to the textbook so often when studying later (though looking at the images will be helpful). Alternatively highlight material in the textbook so you can just read important points when revising later. Don’t just read material relevant to the diagnosis of the CBL case. Your reading should be broader than that such that by the end of 3rd year you have a reasonable understanding of most common and important pathologies e.g. don’t only learn about rheumatic fever and infective endocarditis for the valve pathology case, learn a bit about other valve pathologies also (they may be important causes of incompetence or stenosis and risk factors for infective endocarditis). Integrate content from different disciplines where relevant. For learning histopathological features, you mainly only need to learn and understand the features of • Cell death

• Necrosis: e.g. coagulative (with nuclear karyolysis but preserved cell and tissue outlines) and caseous (amorphous mass of nuclear and cytoplasmic debris)

• Apoptosis: nuclear pyknosis and cell shrinkage • Acute inflammation (mainly neutrophils, macrophages, fibrin, oedema fluid, vasodilation) e.g. in acute appendicitis, pneumonia, acute

cholecystitis, acute pyelonephritis • Chronic inflammation (mainly macrophages, lymphocytes, plasma cells, also germinal centres in certain situations, and granulomatous

inflammation with multinucleate giant cells) and often associated fibrosis e.g. rheumatoid arthritis, Hashimoto’s thyroiditis, rheumatic fever, tuberculosis

• Healing (granulation tissue with fibroblasts, macrophages, new capillaries, lymphocytes, variable amounts of collagen, and scar tissue formation) e.g. skin wounds, infarctions (excluding brain), chronic ulceration and also fracture healing (with callus, including osteoblasts, osteoclasts, osteoid, cartilage, new bone)

• Dysplasia (glandular and squamous – architectural disorganisation, reduced cellular maturation/differentiation and cytological atypia confined to epithelium)

• Features of benign versus malignant lesions (enlarged and pleomorphic nuclei, prominent nucleoli etc) and the features that distinguish the most common malignancies (squamous: eosinophilic cytoplasm, intercellular bridges, keratin pearls, versus glandular: usually formation of glandular structures/acini or mucin production).

There are some exceptions, however, e.g. vascular, glomerular and some liver pathologies do not necessarily fit into any of the above groups. The features in an acute asthma attack are similar to an acute inflammatory process (though the pathogenesis is different), however, eosinophils rather then neutrophils, predominate. You should learn to identify specific cells and features such that you can describe what is there and interpret the image, not just ‘regurgitate’ a memorised list of textbook features that you might expect to be there. Studying for exams By now you should have concise and accurate sets of notes on different topics including lecture notes, notes from your own reading, CBL notes, resource notes etc. Don’t study pathology, anatomy etc in isolation, learn them together with relevant histology, microbiology, physiology, clinical material etc and you will learn to see how it all fits together. Rather than learn material case by case, consider where possible learning material from a body systems point of view (e.g. learn material from all renal cases together).

4

Learning to remember information needs to be an active process. Reading through notes or pages of a textbook once or even several times is unlikely to be effective. Writing vast amounts of notes may not be either, and is not very efficient. Learning material thoroughly involves memorizing and self-testing. Try to memorize information that you have read and understood e.g. from notes. Put the notes down and see how much you can remember (either in your head or by writing it down). Then memorize the information you hadn’t remembered. Go through this process again several days later and see how much you remember. Do this a number of times before exams. The longer you start this process before exams, the better, but it should be at least 4 weeks before exams. Set aside time every week for this. Memorizing and remembering information is easier if you have previously understood it, or most of it, and integrated it with other relevant information or existing knowledge. Learn material thoroughly so you can quickly think of information in a stressful situation e.g. exams. Test yourself also on pots and histopathology images. Images used in exams won’t necessarily be of the same pots or images from resource sessions. You should thus learn to understand the general features of disease processes, not just try to memorize features in specific images/specimens. You may wish to practise answering prepared questions. Resources are available with specific questions and answers (see Resources in Pathology document). Use past MB BS examination papers only to get an idea of the types of question that may be asked, to practice answering questions and to test your knowledge, but be prepared to answer all sorts of question. You need to have the knowledge and skills to be prepared to deal with any situation in medical practice, not just those you’ve come across before. Focussing on learning answers to past exam questions, questions in resource notes or on what you predict will come up in exams is not conducive to developing a solid foundation of knowledge. Don’t memorize ‘model’ answers to sample questions but think about what they are telling you about how to answer questions e.g. amount of detail. Remember that your learning is to develop a solid foundation of knowledge for the practice of medicine, not just to pass exams. Answering exam questions • Examinations are nothing to be afraid of if you have studied hard all semester and know most of the material thoroughly. They are your

opportunity to demonstrate what you have learnt. • Stay calm • Read the questions carefully and answer what is being asked, not what you assume is being asked • Use the clinical information given – it may be relevant. • If asked for the most likely cause/pathology/diagnosis etc – you need to consider what is most likely regarding the prevalence of disease,

age group, gender of the patient, clinical information etc. • Answer the questions clearly and concisely with some detail and appropriate terminology. Don’t assume that the marker will know what

you mean – your answer should clearly demonstrate what you mean • When asked for a diagnosis in a pathology question (or any question) give a pathologic diagnosis e.g. cerebral infarction versus stroke • Be as specific as possible, not vague e.g.

• “Enlargement of the heart” is vague: “Dilatation of the left ventricle or eccentric hypertrophy of the LV” are specific • Tumour or cancer are vague – state the most likely specific type e.g. adenocarcinoma • “White blood cells” and “inflammatory cells” are vague, “neutrophils” and “lymphocytes” are specific

• Explain, pathogenesis: involves mechanisms - step by step covering all important steps, and may require demonstration of other medical sciences e.g. relevant anatomy, microbiology

• Describe: is a description of what is seen e.g. “within the alveolar spaces are neutrophils, strands of fibrin and oedema fluid.” “The alveoli demonstrate acute inflammation” is an interpretation of what is seen, not a description, and pneumonia is a diagnosis, not a description.

“Explain the pathogenesis of” Examples

• Explain the pathogenesis of cholesterol stones of the gallbladder, incorporating the role of any relevant risk factors. Student answer: “Supersaturation of bile, risk factors are female, fat, fertile and forty” is not an adequate answer. “Supersaturation of bile”, while relevant, is not an explanation and “female, fat, fertile and forty” is a list of risk factors that does not incorporate their role in the pathogenesis.

• “Discuss the pathogenesis of atherosclerosis. Include discussion of the role that the main predisposing factors (risk factors) play in its development.” (5 marks) Student answer: “The pathogenesis for atherosclerosis is unknown but the hypothesis is that it is due to a low grade chronic inflammation, from a reoccurring/chronic stress to the artery/arteriole wall. This causes platelets and monocytes to aggregate on the ‘damaged’ site and over time lipid crystals, causing plaque to build up (possibility of calcification) leading to narrowing of the lumen. Risk factors: smoking, hypertension, diabetes, obesity.” (2.5/5) Comment: This answer does not include information on where the atherosclerosis develops (medium and large arteries, intima etc), the role of endothelial dysfunction or all the important histopathological features and how they develop. It does not incorporate the role that the risk factors play in the development of atherosclerosis. There is an error: atherosclerosis does not occur in arterioles.

• “What main specific abnormality would be expected in the Complete Blood Examination (CBE) of a patient with acute appendicitis? Explain its pathogenesis in this setting.” (3 marks) Student answer: “Increased white cell count. Response to inflammation.” (0.5/3) Comment: Increased white cell count is not specific and “response to inflammation” is not an explanation of the pathogenesis. ‘Model’ or sample answer: “Increased neutrophil count. Cytokines including TNF and IL-1 released mainly from macrophages in the acute inflammatory response circulate in the blood and stimulate increased neutrophil release from the bone marrow. Over time there may also be increased production and release of neutrophils.”

• “Explain the most likely pathogenesis of the abnormality demonstrated in the brain.”

5

Answer options: • “Hypertension causes aneurysm formation” • “Hypertension exposes small arteries/arterioles to high pressures, especially in this location where the small lenticulostriate

arteries come directly off the much larger middle cerebral artery. Hypertensive stress -> increased permeability of endothelium to plasma proteins and increased deposition of extracellular matrix in the wall of these small arteries (-> hyaline arteriolosclerosis) and weakening +/- microaneurysm (Charcot-Bouchard) formation -> rupture and haemorrhage in the internal capsule/basal ganglia region.”

Comment: The first answer is not an explanation of the pathogenesis, nor does it specify the type of aneurysm (of which several different types can occur in or around the brain that lead to different locations and patterns of haemorrhage). The second answer is far better.

Other study resources The university Centre for Learning and Professional Development has a variety of learning guides (e.g. Managing your time, Making notes, Exam preparation) at http://www.adelaide.edu.au/clpd/all/learning_guides/