Histopathology and Inflammation

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Questions and Answers

What are the four key characteristics of acute inflammation?

Vasodilation, increased vascular permeability, margination and emigration, and the presence of many neutrophils.

What is the primary focus of cytopathology when examining tissue samples?

Cytopathology primarily focuses on cellular morphology in cell preparations.

Describe two histological changes that can be observed in acute inflammation.

Signs of necrosis such as opaque cytoplasm and loss of cellular detail, along with active tissue repair characterized by cellular proliferation and growing capillaries.

What type of histological changes could be categorized as 'modified'?

Modified histological changes refer to deranged tissues or infiltration, such as inflammation or the abnormal presence of macromolecules. Signup and view all the answers

List three causes of chronic inflammation.

Persistent infections, non-degradable materials, and autoimmune diseases. Signup and view all the answers

What are the key clinical symptoms associated with acute inflammation as identified by histologists?

The key clinical symptoms of acute inflammation include rubor, calor, tumor (swelling), dolor, and loss of function. Signup and view all the answers

What types of white blood cells are primarily involved in chronic inflammation?

Macrophages and lymphocytes are mainly involved, rather than neutrophils. Signup and view all the answers

What are the possible outcomes of acute inflammation?

Recovery where tissue returns to normal, healing with potential scarring, or progression to chronic inflammation. Signup and view all the answers

How does chronic inflammation differ from acute inflammation in terms of duration?

Chronic inflammation lasts for months to years, while acute inflammation lasts from a few hours to a maximum of approximately 14 days. Signup and view all the answers

What are the classifications of growth abnormalities in histopathological changes?

Growth abnormalities can be classified as degenerative changes, such as atrophy and necrosis, or proliferative changes, such as hypertrophy, hyperplasia, metaplasia, dysplasia, and neoplasia. Signup and view all the answers

What is the primary distinction between physiological atrophy and pathological atrophy?

Physiological atrophy refers to normal reduction in size due to developmental processes, while pathological atrophy results from disease or injury. Signup and view all the answers

Describe the intrinsic phase of necrosis and its effect on cellular metabolism.

The intrinsic phase of necrosis involves damage leading to oxygen deprivation, disrupting aerobic metabolism and altering ATP production. Signup and view all the answers

What type of necrosis is characterized by a bright pink eosinophilic stain in blood vessels?

Fibrinoid necrosis is characterized by a bright pink eosinophilic stain. Signup and view all the answers

What cell types are primarily involved in chronic inflammation and how do they differ from acute inflammation?

Chronic inflammation primarily involves lymphocytes, plasma cells, macrophages, giant cells, and epithelioid cells, while acute inflammation involves neutrophils and macrophages. Signup and view all the answers

Explain the differences between caseous and liquefactive necrosis.

Caseous necrosis results in cheese-like, granulomatous tissue typically found in tuberculosis, while liquefactive necrosis leads to liquid pus formation, often seen in brain or bacterial infections. Signup and view all the answers

Describe the process of healing following tissue damage and the role of different tissue types in this process.

Healing involves recovery with no tissue loss (return to normal), regeneration where lost tissue is replaced with identical tissue, and repair where scar tissue forms, depending on whether the tissue is labile, stable, or permanent. Signup and view all the answers

What is meant by gangrenous necrosis, and where is it commonly observed?

Gangrenous necrosis refers to tissue death that typically occurs in limbs and soft tissues due to loss of blood supply or infection. Signup and view all the answers

How does the duration and systemic symptoms of chronic inflammation differ from those of acute inflammation?

Chronic inflammation lasts for weeks to years and shows low-grade fever, weight loss, and variable white cell changes, while acute inflammation is short (days) and typically exhibits fever and neutrophil leucocytosis. Signup and view all the answers

What are the cardinal signs of acute inflammation, and how do they compare to chronic inflammation?

Acute inflammation displays strong cardinal signs, whereas chronic inflammation shows absent or weak signs. Signup and view all the answers

What roles do angiogenesis and fibrosis play in chronic inflammation?

Angiogenesis in chronic inflammation aids in repair and tissue regeneration, while fibrosis indicates the formation of scar tissue, representing a loss of normal tissue function. Signup and view all the answers

Study Notes

Cellular Pathology

Pathology is the study of suffering (logos of pathos)
Histopathology provides diagnostic information from tissue samples, focusing on multicellular structures within tissues.
Cytopathology analyzes cells from preparations, focusing on cellular morphology.

Histopathology in Disease Diagnosis

Histological changes can arise directly from the disease-inducing agent or from the tissue's response to the agent.
Three types of changes include modified tissues (e.g., inflammation, macromolecules), growth abnormalities (e.g., atrophy, necrosis, hypertrophy, hyperplasia, metaplasia, dysplasia, neoplasia), and foreign bodies (e.g., bacteria, fungi, asbestos).

Inflammation

Inflammation is considered a pathological process.
Acute inflammation lasts typically up to 14 days, while chronic inflammation persists for months or years.
Signs of acute inflammation include rubor (redness), calor (heat), tumor (swelling), dolor (pain), and loss of function.
Histologists can indirectly observe clinical symptoms such as rubor (altered blood flow) and tumor (masked by tissue shrinkage).
The presence of inflammation in tissue sections helps identify the location and extent of the disease.

Acute Inflammation Characteristics

Vasodilation
Increased vascular permeability
Margination and emigration of neutrophils
Presence of many neutrophils (polymorphonuclear neutrophils or PMNs/polymorphs)

Histological Changes in Acute Inflammation (1)

Changes in the vascular system are visible (e.g., presence of unusual cells or unusual numbers of cells).

Histological Changes in Acute Inflammation (2)

Degenerative changes include signs of necrosis (e.g., opaque cytoplasm, loss of cellular detail, pyknosis, karyorrhexis, karyolysis, cell debris).
Reactive changes involve active tissue repair, cellular proliferation, mitosis, and growing capillaries.
Outcomes of acute inflammation can lead to recovery, healing (often with scarring), or progression to chronic inflammation.

Chronic Inflammation

Chronic inflammation is distinct from acute inflammation, not simply its continuation.
Causes include persistent infections, non-degradable materials, and autoimmune diseases.
Cardinal signs of acute inflammation are usually absent in chronic inflammation.
White blood cells predominantly include macrophages and lymphocytes (not PMNs).
Plasma cells signify a strong immune response.
Chronic inflammation involves macrophage activity inducing tissue repair and the presence of active fibroblasts, new collagen, and angiogenesis. This process can lead to fibrosis.

Chronic vs. Acute Inflammation - Summary

Acute inflammation has a short duration (days), while chronic inflammation lasts weeks or years.
Cell types in acute include neutrophils and macrophages, while chronic includes lymphocytes, plasma cells, macrophages, giant cells, and fibroblasts.
Acute inflammation has strong cardinal signs, while chronic has absent or weak ones.
Necrosis is usually limited in acute but usually present in chronic.
Fibrosis is usually absent in acute but usually present in chronic.
Systemic symptoms like fever and neutrophil leucocytosis are typically present in acute.
Chronic inflammation often shows low-grade fever, variable white blood cell changes, and increased plasma immunoglobulin.

Healing

Recovery happens when no tissue loss occurs, and the tissue returns to its normal state after minor damage.
Regeneration involves tissue replacement with identical new tissue.
Repair involves scarring.
Tissue repair/regeneration capacity depends on tissue type.
- Labile tissues (e.g., epithelial) can repair or regenerate.
- Stable tissues (e.g., liver) can regenerate but to a certain extent given damage.
- Permanent tissues do not fully regenerate and have repaired tissue lacking full functionality.

Degenerative Tissue Growth Abnormalities – Atrophy

Atrophy is the shrinkage of an organ or tissue, which can be pathological or physiological.
Physiological atrophy is related to involution (e.g., thymus).
Examples of atrophy include: disuse, neurogenic, hormonal, ischemic, pressure, brown, senile, and generalized atrophy

Degenerative Tissue Growth Abnormalities - Necrosis

Necrosis is messy cell death with a slow, destructive response to acute insult.
Intrinsic phase involves damage leading to oxygen lack, disruption of normal aerobic metabolism, decreased ATP production, increased lactate and CO2 levels, decreased pH, and inhibited enzyme activity.
Different forms of necrosis include coagulative, caseous, fibrinoid, liquefactive, and gangrenous necrosis

Tissue Overgrowth

Hypertrophy is an increase in cell size without an increase in cell numbers.
Hyperplasia is an increase in cell numbers.
Metaplasia is the transformation of one fully differentiated cell type into another with different cellular capabilities.
Dysplasia is an abnormality of cell differentiation.

Neoplasia (Tumors)

Neoplasms are tumors.
Benign neoplasms are characterized by small size, well-defined borders, differentiation resembling the tissue of origin, slow growth, rare mitotic figures, no necrosis, no invasion, and no metastasis.
Malignant neoplasms are characterized by large size, poorly defined borders, variable differentiation, rapid growth, common mitotic figures, necrosis, invasion, and metastasis.

Nomenclature

Benign epithelial tissue tumors are called papillomas (surface epithelium) and adenomas (glandular epithelium).
Malignant epithelial tissue tumors are called squamous cell carcinomas and adenocarcinomas.
Mesodermal tumors have _oma suffixes (e.g., fibroma, lipoma) or _sarcoma suffixes (e.g., fibrosarcoma, liposarcoma).

Dangers of Neoplasms

Invasiveness and metastasis are dangers associated with neoplasms.
To successfully metastasize, cells must detach from the original tumor, enter a suitable transport medium (e.g., lymph, blood), survive in circulation, migrate to new tissue, and divide at a new site.
Two mechanisms proposed for metastatic specificity are site of secondaries controlled by lymph or blood flow patterns and the seed and soil hypothesis, where the secondary site is determined by cell growth requirements.

Histological Recognition of Malignancy

Cellular changes in malignancy include variation in nuclear size and shape, increased nucleo-cytoplasmic ratio, increased chromatin content, altered staining (e.g., hyperchromatic, hypochromatic, polychromatic), frequent cell divisions, variation in cytoplasm size/shape, abnormal staining, and altered antigens.
Tissue changes in malignancy can include inflammation, abnormal maturation, invasion, and metastasis.

Grading of Malignant Neoplasms

Histological assessment of malignancy is based on cell morphology and differentiation with low grades being least malignant and high grades most malignant.

Staging of Malignant Neoplasms

Staging systems (e.g., TNM - Tumor, Node, Metastasis) describe tumor size, lymph node involvement, and metastasis.
Additional letters (e.g., p - pathological, c - clinical) describe details about the surgically removed tissue or the observation before surgery, respectively.

Ageing and Senescence

Aging refers to the chronological aging process.
Senescence describes the biological aging state when tissues' effectiveness declines or become less active.
Multiple organ systems undergo changes associated with aging, leading to several diseases.

Apoptosis

Apoptosis is programmed cell death that removes unwanted or damaged cells precisely without causing inflammation.
Characteristic features include cell shrinkage and condensation, cytoskeleton collapse, nuclear envelope disassembly, chromatin condensation and fragmentation, caspase activation for intracellular proteins, endonuclease activation for cleavage between nucleosomes, nucleus condensation into crescent shapes, formation of apoptotic bodies, and changes in membrane lipids/carbohydrates to mark them for phagocytosis.

Apoptosis vs Necrosis: Comparison

Apoptosis affects isolated cells, while necrosis affects groups of cells/tissue tracts.
Apoptosis shows chromatin margination, and cell fragments into bound structures with cell shrinkage, and intact organelles, while necrosis exhibits pyknosis, karyorrhexis, karyolysis, coagulation of cell contents, cell swelling, disrupted cell outlines, and ruptured lysosomes.
Apoptosis has no inflammation, and phagocytosis is rapid with many cell types, whereas necrosis has inflammation, phagocytosis is slower (only ingestion by macrophages), and is a pathological process.

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Description

This quiz covers key concepts in histopathology, focusing on acute and chronic inflammation. Participants will explore the characteristics, symptoms, and histological changes associated with inflammation, along with necrosis and atrophy distinctions. Delve into the intricacies of cellular responses in pathological conditions.