PATHOLOGICAL ANATOMY: HISTORY, OBJECT OF STUDY, METHODS - ANATOMY AND PHYSIOLOGY - 2024

The pathology, or simply pathology is the branch of anatomy studying morphology, development, the causes and effects of changes of organs, tissues and cells from disease, both innate and acquired, and traumatic injury, both accidental and provoked.

The term pathological anatomy is derived from the Greek (ana = separate; tome = cut; pathos = suffering; logos = study). It is divided into animal pathology, which includes human pathology, and plant pathology.

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Human pathology is one of the foundations of medicine. It is the bridge that connects anatomy, which is a preclinical science, with the clinic. One of the most famous quotes from Sir William Osler (1849–1919), considered the founder of modern medicine, is: "Your practice of medicine will be only as good as your understanding of pathology."

Human pathology also encompasses forensic medicine, which uses autopsies to determine the causes and timing of death, and the identity of the deceased.

Notable in this field are: Hippocrates, (460–377 BC), who is considered the founder of medicine; Andreas Vesalius, (1514–1564), considered the founder of modern anatomy; Rudolf Virchow (1821–1902) considered the founder of pathology.

History

Pathological anatomy in ancient times

Since prehistoric times, diseases have been attributed to supernatural causes, such as spells, spirits, and divine wrath. For example, for the ancient Greeks, Apollo and his son Asclepius were the main gods of healing. For her part, Dhanvantri is the deity of medicine in India, in fact many health institutions in that country bear her name.

Hippocrates separated medicine from the supernatural. He believed that diseases were due to the imbalance between four basic humors: water, air, fire, earth. His writings, dealing with anatomy, disease, treatment, and medical ethics, were the foundation of medicine for nearly two thousand years.

Cornelius Celsus (53 BC –7 AD), described the four cardinal symptoms of inflammation (redness, edema, heat, pain) and insisted on hygiene and the use of antiseptics.

Claudius Galenus (129-216) believed in the existence of three body systems (brain and nerves; heart; liver and veins) and that diseases are due to the imbalance between four body fluids: blood, phlegm, black bile, yellow bile (theory humoral).

Towards the end of the Middle Ages (X – XIII centuries) there was a return to supernatural explanations. Thus, epidemics were considered divine punishment for sins committed. The dissection of the human body was prohibited so as not to injure the soul that it was believed to house.

Beginning of modern pathological anatomy

In 1761, Giovanni Battista Morgagni (1682–1771), known in his time as "His Anatomical Majesty," demolished Galenus' humoral theory. He published a book based on more than 700 autopsies establishing the relationship between cause, injuries, symptoms and disease, thus laying the foundations of the clinical-pathological methodology.

Morgagni's book marks the beginning of "morbid anatomy," which is the name given to pathological anatomy in the 18th and 19th centuries. In 1795, Matthew Baillie (1761–1823) published Morbid anatomy, the first book of pathological anatomy in English.

At the end of the 18th century, the brothers William (1718–1788) and John Hunter (1728–1793) created the world's first collection of comparative anatomy and pathology, containing numerous samples of clinical pathology. This collection, now known as the Hunterian Museum, is kept at the Royal College of Surgeons in London.

Also towards the end of the 18th century, Xavier Bichat (1771–1802), who performed more than 600 autopsies in a single winter, macroscopically identified 21 types of tissue. Bichat studied how these tissues were affected by diseases. For this reason, he is considered a pioneer of histopathology.

Development in the 19th century

Pathology studies allowed the recognition of numerous diseases, named after their discoverers, such as Addison, Bright, and Hodgkin's and Laennec's cirrhosis.

Morbid anatomy reached its zenith thanks to Carl von Rokitansky (1804–1878), who performed 30,000 autopsies in his lifetime. Rokitansky, who unlike other surgeons of his time did not practice clinical practice, believed that pathologists should limit themselves to making diagnoses, which is their normal role today.

The discovery by Louis Pasteur (1822–1895) that microorganisms cause disease demolished the hitherto prevalent theory of spontaneous generation.

Rudolf Virchow (1821–1905), went further than Xavier Bichat, using the microscope to examine diseased tissues.

During the second half of the 19th century, pathological anatomy underwent a great development as a diagnostic discipline thanks to technical advances, including the development of better microtomes and microscopes, and the invention of cell fixation and staining procedures.

Julius Cohnheim (1839–1884), introduced the concept of examining diseased tissue samples while the patient is still on the operating table. However, until the end of the 19th century, pathological anatomy continued to focus on autopsies.

Development in the 20th and 21st centuries

At the beginning of the 20th century, pathological anatomy was already a mature science based on the interpretation of macroscopic and microscopic structures, many times perpetuated by photographic images. This has changed little, since at present, pathological anatomy continues to be a mainly visual discipline.

During the second half of the 20th century, thanks to technological advances (microscopy, robotics, endoscopy, etc.), pathological anatomy has undergone substantial progress linked to an exponential increase in the diversity, quality, and magnifications of images of pathological material, as well as in the computer systems to store and analyze them.

The atlases of anatomy and pathology contain ever better and more varied images. For both specialists and students, this has reduced the need to observe preserved specimens, increased ease of learning, and improved disease diagnosis, saving lives.

The possibility of studying diseased tissues at the molecular level has also become very important. This has allowed much more precise diagnoses, leading to tailor-made therapies, especially in cases of cancer, immunological diseases and genetic disorders.

Basic terminology of pathological anatomy

Acute and chronic

The former refers to diseases that appear and develop rapidly. The second to diseases that develop slowly and have a long course.

Diagnosis and prognosis

The former refers to the identification of a disease, or the process of identifying its cause. The second refers to a prediction of the course or consequences of a disease.

Etiology and pathogenesis

The former refers to the underlying cause of pathological events. The synonyms cryptogenic, essential, and idiopathic are used to refer to diseases of unknown etiology. The second refers to the etiological mechanism that produces the symptoms of a disease.

Incidence and prevalence

The former refers to the number of new cases of a disease diagnosed in a population during a certain period. The second refers to the number of cases present in a population at a specific moment.

Morbidity and mortality

The former refers to the extent to which a patient's health is affected by illness. The second refers to the percentage of deaths associated with a disease.

Symptom and syndrome

The first is a manifestation of the presence of a disease. The second is a combination of symptoms that appear together, suggesting a common underlying cause.

Main processes studied

Apoptosis

Natural programmed death of old, unnecessary or diseased cells. When it is deficient it is implicated in cancer. When it is excessive it causes neurogenerative diseases (Alzheimer, Huntington, Parkinson).

Atrophy and degeneration

Decrease in the volume and function of an organ or tissue due to reduction in cell size or number. It can be the result of excessive apoptosis, or aging, physical or chemical trauma, vascular disease, vitamin deficiencies, or genetic defects.

Dysplasia

Abnormal growth of organs and tissues. It is divided into hyperplasia, metaplasia and neoplasia.

Hyperplasia is the enlargement of an organ or tissue due to the non-cancerous multiplication of its cells.

Metaplasia is the alteration of a tissue due to the transformation, generally non-cancerous, of its cells into other types of cells.

Neoplasia is the uncontrolled proliferation of cells that leads to the formation of cancerous or non-cancerous tumors.

Inflammation

Self-protective reaction of tissues in response to irritation, physical and mechanical trauma, or infection. It can be caused by rheumatoid arthritis and autoimmune diseases.

Necrosis

Cell death in a tissue due to: 1) ischemia, which can lead to gangrene; 2) infection; 3) heat, cold or some chemical agent; 4) radiation.

Methods and techniques

Histopathology

Classic pathology is known as histopathology. It is based on the observation, with the naked eye and the microscope, of the structural changes experienced by the tissues as a result of pathological processes. It is applied to corpses (autopsy), or to samples obtained from patients during surgeries or through biopsies.

In daily practice, histopathology remains the predominant branch of pathological anatomy.

Biopsies are obtained by making a small local incision with a scalpel, with the help of forceps or forceps, by aspiration with a hypodermic needle or endoscopically.

The observation of samples with the microscope is facilitated by the previous use of various techniques of fixation, sectioning and tissue staining.

Fixation techniques include freezing and embedding of tissues in paraffin blocks.

Sectioning consists of creating histological sections, typically 5–8 µm thick, using a microtome.

Staining is performed using reagents that color tissues and cells (eg, hematoxylin, eosin, Giemsa) or by histochemical and immunohistochemical processes.

The types of microscope used include the optical, the electronic, the confocal, the polarizing, and the atomic force.

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The use of a great diversity of methods and techniques, originating from other disciplines of medicine and biology, has substantially improved the understanding of pathological processes and diagnostic precision. According to its methodology, several specialized branches of pathological anatomy can be defined.

Clinical pathology is concerned with quantifying the biological, biochemical, and chemical constituents of blood serum and plasma, and of other body fluids, such as urine and semen. It also handles pregnancy tests and identifying tumor types.

Immune pathology is concerned with detecting abnormalities of the immune system, including the causes and effects of allergies, autoimmune diseases, and immunodeficiency.

Microbiological pathology identifies parasites, fungi, bacteria and viruses implicated in diseases, and assesses the damage caused by these infectious agents.

Clinical, immunological and microbiological pathologies are highly dependent on the use of commercial test systems or reagents, which save a lot of time and minimize errors.

Molecular pathology is mainly based on the application of the polymerase chain reaction (PCR), better known by its acronym in English (PCR).

Genetic pathology deals with blood groups, innate metabolic errors, chromosomal aberrations, and congenital malformations.

Roles of the pathologist

It contributes fundamentally to the management of patients through the diagnosis of diseases.

It identifies functional damage at the organ, tissue and cell levels and the chain of effects, expressed in abnormal structural changes, of pathological processes.

He performs autopsies to determine the causes of death and the effects of the treatments.

Collaborate with justice to: 1) identify common criminals and establish their responsibilities; 2) test and evaluate the damage caused to health by food, pharmacological and chemical products of commercial origin.

Research examples

On September 19, 1991, at an altitude of 3,210 m in the Italian Alps, a frozen body was discovered accompanied by ancient clothing and utensils. The news caused a stir when it was determined that the individual, since then nicknamed Ötzi, had died more than 5,000 years ago.

The autopsy of the body and the study of the other remains allowed to determine, among many other things, that Ötzi was murdered in spring, he was approximately 46 years old, he was 1.60 m tall, weighed about 50 kg, he had brown hair and eyes, he had a group O + blood, suffered from arthritis, tooth decay, Lyme disease, had intestinal parasites and wore tattoos.

Through the histopathological study it has been determined that: 1) the joint consumption of marijuana and tobacco produces additive damage to the trachea and bronchi; 2) although, by itself, the consumption of smoked cocaine produces small damages, it considerably increases the bronchial damage produced by tobacco.

Corroboration through histopathological techniques is essential to validate computerized methods of image analysis of diseased tissues for diagnosis and prognosis purposes. This is the case, for example, of computerized analyzes of breast and prostate cancers.

References

1. Allen, DC, Cameron, RI 2004. Histopathology specimens: clinical, pathological and laboratory aspects. Springer, London.
2. Bell, S., Morris, K. 2010. An Introduction to microscopy. CRC Press, Boca Raton.
3. Bhattacharya, GK 2016. Concise pathology for exam preparation. Elsevier, New Deli.
4. Bloom, W., Fawcett, DW 1994. A textbook of histology. Chapman & Hall, New York.
5. Brem, RF, Rapelyea, JA, Zisman, G., Hoffmeister, JW, DeSimio, MP 2005. Evaluation of breast cancer with a computer-aided detection system by mammographic appearance and histopathology. Cancer, 104, 931–935.
6. Buja, LM, Krueger, GRF 2014. Netter's illustrated human pathology. Saunders, Philadelphia.
7. Carton, J. 2012. Oxford handbook of clinical pathology. Oxford, Oxford.
8. Cheng, L., Bostwick, DG 2011. Essentials of anatomic pathology. Springer, New York.
9. Cirión Martínez, G. 2005. Pathological anatomy. Topics for nursing. Editorial Medical Sciences, Havana.
10. Cooke, RA, Stewart, B. 2004. Color atlas of anatomical pathology. Churchill Livingstone, Edinburgh.
11. Drake, RL, Vogl, W., Mitchell, AWM 2005. Gray: Anatomy for Students. Elsevier, Madrid.
12. Fligiel, SEG, Roth, MD, Kleerup, EC, Barskij, SH, Simmons, MS, Tashkin, DP 1997. Tracheobronchial histopathology in habitual smokers of cocaine, marijuana, and / or tobacco. Chest, 112, 319–326.
13. Kean, WF, Tocchio, S. Kean, M., Rainsford, KD 2013. The musculoskeletal abnormalities of the Similaun Iceman ('ÖTZI' '): clues to chronic pain and possible treatments. Inflammopharmacology, 21, 11–20.
14. Kumar, V., Abbas, AK, Aster, JC 2018. Robbins basic pathology. Elsevier, Philadelphia.
15. Lindberg, MR, Lamps, LW 2018. Diagnostic pathology: normal histology. Elsevier, Philadelphia.
16. Lisowski, F. P, ​​Oxnard, CE 2007. Anatomical terms and their derivation. World Scientific, Singapore.
17. Maulitz, RC 1987. Morbid appearances: the anatomy of pathology in the early nineteenth century. Cambridge University Press, New York.
18. Mohan, H. 2015. Textbook of pathology. Jaypee, New Deli.
19. Ortner, DJ 2003. Identification of pathological conditions in human skeletal remains. Academic Press, Amsterdam.
20. Persaud, TVN, Loukas, M., Tubbs, RS 2014. A history of human anatomy. Charles C. Thomas, Springfield.
21. Riede, U.-N., Werner, M. 2004. Color atlas of pathology: pathologic principles, associated diseases, sequela. Thieme, Stuttgart.
22. Sattar, HA 2011. Fundamentals of pathology: medical course and step I review. Pathoma, Chicago.
23. Scanlon, VC, Sanders, T. 2007. Essentials of anatomy and physiology. FA Davis, Philadelphia.
24. Tubbs, RS, Shoja, MM, Loukas, M., Agutter, P. 2019. History of anatomy: an international perspective. Wiley, Hoboken.