Pathological anatomy

The pathological anatomy (AP) is the branch of medicine that deals with the study, by means of morphological techniques, of the causes, development and consequences Of diseases. All this requires a histological process of the piece to be studied, be it a biopsy, tissue or organ, a fundamental part of which is the histological section.

The ultimate goal of this specialty is the correct diagnosis of biopsies, surgical specimens, cytology and autopsies. In the case of medicine, the fundamental field is that of human diseases. Pathological anatomy is a medical specialty that has a basic body of doctrine that determines that it is, on the one hand, an autonomous academic discipline and, on the other, a functional unit in medical care. It is achieved through a MIR and a four-year specialization.

Etymology

The word pathology comes from the Greek and is the study (logos) of suffering or damage (pathos).

Pathology is one of the fundamental pillars of medicine and an essential basic discipline for doctors, veterinarians and other health professionals.

The interpretation of the symptoms of the different diseases or alterations found in the examination of the patients requires knowledge of the entire spectrum of lesions that occur in each of the tissues or organs.

Pathology encompasses all aspects of disease, primarily at the morphological cellular level. The alterations are studied with various methods, ranging from molecular to macroscopic pathology, which are translated into the changes observed in microscopy (optical or conventional microscopy and electron microscopy) and macroscopy; Various techniques are used, ranging from histochemistry and immunohistochemistry to ultrastructure and molecular pathology techniques (FISH, PCR).

History

Hippocrates was the first to recognize that the pathology was based on an alteration of the humors and their relationship, based on the naturalistic philosophy of Empedocles who had already described those humors: blood, lymph, black bile and yellow bile.

Galen kept the theories of Hippocrates in force throughout the medieval period, turning them into dogmas.

Gradually, authors began to emerge who did not see Hippocrates' theories as absolute truths. From the Renaissance, the first autopsies began to be carried out, a new current of authors began who believed only what they could see, definitively moving away from the dogmatic ideas that had prevailed up to that moment.

Antonio Benivieni is considered the father of Pathological Anatomy; requested permission from relatives to carry out post-mortem examinations in enigmatic cases. He kept careful records and these were published by his brother in 1507, as the hidden causes of diseases. Included in the 111 short chapters of this treatise are descriptions of 20 autopsies. However, Benivieni made "incisions" in cadavers, but not complete dissections, and the results are superficial. Vesalius based his study of the disease on morphological aspects, leaving aside the dogmatism imposed at the time.

This is how organic anatomy was born, which directly relates morphology to the alterations and symptoms that accompany the disease.

The authors who were appearing at the time and who discovered how valuable autopsy was for the study of medicine, such as Morgagni, began to understand that the observation and study of morphological alterations were the fundamental basis for understanding The diseases.

In the late 18th century, Bichat introduced the concept of weaving. Trying to find simple units that make up the organs, the world of pathology thus entered the tissue era.

Already in the 19th century, and thanks to the development of the optical microscope, the cell theory was introduced, which provided another level in the organization of living beings. Robert Hooke was the first to talk about cork cells. In Germany they began to associate cells and their alterations with pathologies.

Claude Bernard also added that the physical and chemical characteristics of the cell and its alterations are equally related to the disease

In recent times, pathology has undergone extraordinary development, thanks to advances in the field of technology, medicine, biology, etc. Likewise, it can be affirmed that pathological anatomy is in continuous development.

Pathological responses

General pathology deals with the study of the foundations and development of basic pathological response processes, ranging from cellular adaptation to changes in the environment, injury, and cell death, their causes and their consequences, the disorders of the growth of cells, tissues and organs, as well as the responses of the individual to the various injuries caused by external and internal agents and the repair mechanisms of these injuries. According to the pathology there are three basic causes that originate the diseases that are:

Inflammation

It's the diseases that end up in -itislike appendicitis,

Degeneration

It's the diseases that end up in -osisLike osteoarthritis.

Uncontrolled cell growth

It's the diseases that end up in -Like melanoma.

The special pathological anatomy deals with the study of the specific responses of each tissue or organ.

The teratological anomalies teratological anomalies are those that cause anatomical deformations, but that, in general, do not involve the total structure of the organism.

some examples of teratological anomalies are the monarchial

Aspects of the disease

The four aspects of a disease, which form the core of pathology are:

1. Etiology: It is the causes of the disease.
2. Patogenia: They are the mechanisms by which the disease develops.
3. Morphological changes: They are the structural alterations that occur in cells and organs.
4. Clinic: They are the functional consequences of morphological changes.

Pathologists/pathologists are specialists in pathology and are in charge of this study of the morphological changes of diseases. In the hospital environment we can distinguish, grosso modo, between surgical pathology, which analyzes tissues from the biopsy or surgical piece; cytological pathology, which analyzes cells from brushings or liquids, and autopsy pathology, which analyzes the causes of death in cadavers.

There are diseases sine materia in which a clear morphological alteration cannot be observed, as occurs with most psychiatric diseases and many functional disorders, such as irritable bowel syndrome.

Cellular pathology and interstitial spaces

Cell injury

Cells have an extraordinary capacity for adaptation. When this capacity for cell adaptation is exceeded, cell damage arises, which can be reversible or irreversible.

Causes of injury

• Ischemy and hypoxia
• Traumatism
• Chemical substances
• Infectious agents
• Thermal variations
• ionizing radiation
• Inmunitory agents
• Genetic alterations
• Nutritional imbalance
• Accumulation of intracellular substances

Cellular adaptation

Faced with various stimuli towards the cell, it undergoes some changes that help it to adapt to the situation. These changes are:

• Atrophy: decrease in the size of the organ due to poor stimulation (this is what happens to quadriceps for example when a patient is encamed for a long period of time)
• Hypertrophy: opposite situation in which the size of the organ increases by overestimation. It detracts from an increase in the size of the cells that form the tissue and is not an increase in its number. Hypertrophy can be physiological (those of an athlete) or pathological
• Hyperplasia: in this case it does increase the number of cells in the organ, causing it to increase its size, can also be the result of a hormonal physiological process (increase in the size of breasts during breastfeeding), compensatory physiological (when a section of the liver is removed) or of a pathological process (increase in the endometrial due to excessive hormonal stimulation derived from the existence of an ovarian tumor).
• Metaplasia: change of mature tissue by another also mature. It is usually the result of an aggression, the metaplasia of respiratory epithelium should be highlighted by another type of malpygian in smokers. The epithelial tissue changes to adapt to the aggression of smoke. The risk of metaplasia is that this tissue becomes much more susceptible to malignancy

Cell death

When all adaptation and resistance mechanisms have been exhausted, cell death occurs. The cell can die in two different ways:

• Necrosis: occurs due to acute cell injury in pathological conditions, that is, derived from some non-physiological situation that causes cell death (may be called murder). Necrosis is characterized by its violence, the cell is broken outside by releasing substances that are harmful to the tissue in which it is. Typical changes of a necrotic cell are: picnosis, cariorexis and cariolysis. Depending on the injury mechanism there are several types of necrosis:
  • Coagulative necrosis: it occurs because of thysular ischemia that generates coagulation of intracellular proteins, making it unviable (that is, for example, in acute myocardial infarction). The necrosis area is replaced by fibrous tissue
  • Licuefactive necrosis: in this case a rapid autólysis occurs that makes the necrosada zone liquefied. It is typical of the central nervous system
  • Fat necrosis
    • Traumatic: It is not usual, it occurs due to trauma that surpasses cellular adaptation capabilities
    • Enzymatic: occurs when digestive enzymes (lipases, proteases, etc.) are released into the medium without control, or are activated in a place not suitable. This occurs for example in pancreatitis, where the "storage" produced by obstruction of the Wirsung duct makes pancreatic digestive enzymes active inside it.
  • Homeifying Necrosis: is necrosis typically produced in tuberculosis
• Apoptosis: programmed cell death. In this case a series of physiological or pathological events generate biochemical changes in the cell and this "decides" its own death, in an orderly manner, disintegrating into small gallbladders that will be made by macrophages and without greater impact on the tissue in question (it could be called suicide)

Storage diseases: thesaurysmosis

It is a generic term that designates diseases that are characterized by a pathological accumulation of endogenous or exogenous substances in the tissues produced by an enzymatic deficiency. It is the morphological expression of a metabolic disorder that generates an unusual accumulation of a certain substance inside the cell, the most frequent being glucogenic and cystinic.

The morphological lesion can be reversible or irreversible. Some of these disorders only have biochemical repercussions.

The general causes of these processes are:

1. Increased synthesis of such substance.
2. Decrease in his catabolism.
3. Inability to degrade it.

Diseases caused by the accumulation of substances include:

• Thessaurismis of triacilglycerides: They can be stored abnormally in the parenchymatous cells of an organ (steatosis) or in the adipose tissue (lipomatosis).

1. La stoatosis it will typically occur in the cells of the liver, kidney, skeletal muscle and heart muscle. It is due to an increase in the contribution (major intake) of fats, to a decrease in ß-oxidation, decrease of proteins (thanks to proteins can be carried by the blood, if they decrease it is not possible to mobilize them, being stored) or because of some toxic. Steatosis includes hepatic steatosis, kidney steatosis (due to hypoxic processes such as heart failure or glomerulonephritis, muscle steatosis and Reye syndrome.
2. La lipomatosis: may be a widespread increase in adipose (obesity) or local tissue at an organ level. In organs that involve the age (last, bone marrow...) it is a normal process. If it occurs otherwise, such as in the skeletal muscle, a pathological process (myopathies and muscular dystrophies) is present.

• Thessaurismsis of cholesterol: Cholesterol is the basis molecule of steroids and bile acids, and it also has a structural mission in the cell membranes to which it gives flexibility. In normal conditions it is not possible to see it through optical microscopy, the fact of seeing it is of itself pathological. When it accumulates it does it in the form of crystals and in inappropriate amounts is a large proinflammatory. The lymphocytes are ready to surround it and to achieve it they merge by forming multinucleated giant cells of foreign body. If the process is slow, the macrophages are fagociting it by becoming multi-vesiculated or xantomatous cells.

Inflammation

It is one of the broad categories of tissue response to disease. They are diseases that end in -itis, such as appendicitis, cervicitis,...

Inflammation is divided into acute and chronic, although in reality both types often form a continuum.

Acute inflammation has three main and interrelated components:

• Vascular dilation
• Endothelial activation
• Activation of neutrophils

Results of acute inflammation

If the patient survives, acute inflammation has four main possibilities of evolution:

• resolution,
• cure for fibrosis,
• formation of abscess and
• progression toward chronic inflammation.

Chronic inflammation can be subdivided into the following types:

• Unspecific chronic inflammation: follows unresolved acute inflammation.
• Specific chronic inflation: in response to certain types of causal agents.
• Granulomatous inflammation: is a specific chronic inflammation variety characterized by the presence of granulomas.

The chronic inflammatory infiltrate, in contrast to the marked predominance of neutrophils that characterizes the acute inflammatory response, is dominated by:

• tissue macrophages,
• lymphocytes and
• plasma cells

Chronic inflammation usually heals by fibrosis.

Agents capable of causing chronic granulomatous inflammation include:

• Low toxicity microorganisms such as Treponema Pallidum, the causal agent of syphilis.
• Infectious microorganisms that grow within cells, for example Mycobacterium Tuberculosis.
• Fungal infections, protozoa and parasites.
• Strange body reaction.
• Inert materials such as silica, talcum, asbestos or beryllium.

The defining feature of granulomatous inflammation is the presence of:

• activated and activated epithelioid macrophages
• Multinucleated giant cells derived from macrophages.

Epithelioid macrophages get their name from their histologic appearance, which is reminiscent of epithelial (squamous) cells.

A special granulomatous chronic inflammation is tuberculous. Tuberculosis is a contagious bacterial infection caused by Mycobacterium tuberculosis (TB) that first affects the lungs, but can later spread to other organs.

The characteristic histologic lesion is the tuberculous granuloma. In the center of it there is an area of:

• homemade necrosis containing tuberculosis bacilos; these microorganisms can only be shown by specific staining techniques for resistant acid-alcohol baciles. The home area is surrounded by an area of epitelioid macrophages with abundant eosinophilic cytoplasm. Some macrophages melt together to produce multinucleated giant cells called giant Langhans cells. In the periphery of the macrophages there is a rebound of Linfocitos

Vascular pathology

- Congestion (hyperemia):

It is the increase in the amount of blood present in the vessels of an organ or tissue. There are two types of congestion: active and passive.

- Hemorrhage:

It is the exit of blood from the blood vessels.

- Pathological thrombosis:

Thrombosis is the formation, during life, of a blood clot, which is called a thrombus, inside the cardiovascular system. A collection of blood in the tissues, outside the cardio-vascular system, is a hematoma.

- Embolism:

It is the projection of a foreign body into the circulatory current and stopped in a vessel of insufficient caliber to allow its passage.

- Hypoxia. Ischemia. Heart attack.

Hypoxia. It is insufficient oxygenation of the tissues.

Ischemia. It is the cessation or extreme reduction of blood supply to an organ.

Heart attack. It is a focus of necrosis secondary to the sudden cessation or extreme reduction of blood supply to a tissue or organ. It is the consequence of acute ischemia. The slow obstruction of a vessel can produce ischemia and not infarction.

- Edema: It is the pathological increase of liquids in the tissues.

- Crash (Collapse): Shock is a circulatory failure associated with generalized loss of tissue perfusion (circulation).