Necrosis and apoptosis/inflammation Flashcards
What is necrosis?
-Necrosis is defined as abnormal tissue death during life. -Necrosis is ALWAYS pathological and is accompanied by inflammation.
-Groups of cells are involved and they undergo swelling and lysis.
-Necrotic cells are phagocytosed by inflammatory cells.
What are the different types of necrosis?
Coagulative (structured): most common form due to interruption of blood supply
Liquefactive: Occurs in the brain
Caseous: TB
Fat necrosis: Can follow direct trauma (e.g. in breast) or enzymatic lipolysis (pancreatitis)
Gangrenous necrosis: can be wet, dry or gaseous. Tissue appears green or black due to
haemoglobin breakdown
What is apoptosis?
Apoptosis is the process of programmed cell death. Unlike necrosis, apoptosis produces apoptotic bodies that phagocytic cells remove before stimulating any inflammatory reaction
What is the difference between apoptosis and necrosis?
Necrosis is ALWAYS pathological and is accompanied by inflammation.
Apoptosis is the process of programmed cell death. Unlike necrosis, apoptosis produces apoptotic bodies that phagocytic cells remove before stimulating any inflammatory reaction
What is a neoplasm?
A neoplasm is an abnormal growth of tissue which displays:
Uncoordinated growth
Growth which exceeds that of the normal tissue
Growth which continues despite removal of the original stimulus
Note: The term neoplasm is synonymous with the term tumour
How are neoplasms classified?
Can be divided into benign or malignant
Malignant neoplasms are then subdivided into primary or secondary
How can neoplasms be classified according to cell type?
One cell type:
Epithelial: papilloma, adenoma, carcinoma
Mesenchymal: fibroma, lipoma, sarcoma
Lymphoma
More than one cell type from one germ layer:
Pleomorphic adenoma, fibroadenoma
More than once cell type from more than one germ layer:
Teratomas (can be benign or malignant)
What is hyperplasia?
Hyperplasia is an increase in the size of an organ or tissue through an increase in the
NUMBER of cells. The cells are of normal size and morphology
Can you give 2 physiological and 2 pathological examples of hyperplasia?
Physiological examples: Breast tissue during puberty, thyroid during pregnancy
Pathological examples: Benign prostatic hyperplasia, adrenals in Cushing’s
What is hypertrophy?
Hypertrophy is an increase in the size of an organ or tissue through an increase in the SIZE of
the cells. The number of cells remains the same, as does the morphology.
Can you give 2 physiological and 2 pathological examples of hypertrophy?
Physiological examples: Skeletal muscle with exercise, uterus in pregnancy
Pathological examples: Cardiomyopathy, thyroid in Graves’ disease
What is a hamartoma and can you name some examples?
A hamartoma is a tumour-like malformation
-composed of a disorganised arrangement of different amounts of tissue normally found at that site
-It grows under normal growthcontrols.
Examples: Peutz-Jegher’s polyps of the bowel; haemangiomas; lipomas
What is metaplasia and can you give some examples?
Metaplasia is a REVERSIBLE replacement of one fully differentiated cell type with another differentiated cell type.
Examples include:
-Barrett’s oesophagus secondary to GORD(Change from stratified squamous to columnar epithelium)
-Transformation zone of the cervix secondary to HPV (Change from columnar epithelium to
stratified squamous)
What is dysplasia?
Dysplasia is disordered cellular development characterised by increased mitosis and pleomorphism but WITHOUT the ability to invade the basement membrane and metastasise.
Note: Severe dysplasia = carcinoma-in-situ
Define the term pleomorphic
Occurring in various distinct forms. In terms of cells, having variation in the size and shape of cells or their nuclei
What are carcinomas and sarcomas, and how do they typically spread? Are there exceptions?
A carcinoma is a malignant tumour of epithelial cells
A sarcoma is a malignant tumour of connective tissue
Carcinomas typically spread by the lymphatic route
Sarcomas typically spread by the haematogenous route
Note: An exception to this is follicular thyroid carcinomas which spread via the
haematogenous route
What type of epithelium lines the oesophagus?
Stratified squamous
What is metastasis?
Metastasis is the survival and growth of cells that have migrated from a malignant neoplasm to a site distant from the primary neoplasm
What are the routes by which tumours spread? Which cancers spread via each?
Local invasion
Lymphatics – most carcinomas
Blood – sarcomas and follicular carcinoma of the thyroid
*Transcoelomic – carcinoma of the stomach, ovary, colon, pancreas
CSF – CNS tumours
Iatrogenic – Implantation/seeding during surgery/FNA/biopsy
*The spread into body cavities occurs by the seeding surface of the peritoneal, pleural,
pericardial or subarachnoid spaces
What is acute inflammation?
Acute inflammation is the body’s stereotypical response to tissue injury. It is characterised
by:
Heat, pain, redness, swelling (calor, dolor, rubor, tumor)
+/- loss of function (functio laesa)
+/- secretions
What are the stages of acute inflammation?
- Vasodilation
- Increased vascular permeability
- Migration of white cells through the vessel walls
- Phagocytosis
- Either resolution or progression to chronic inflammation
Name some chemical mediators that participate in acute inflammation
Vasoactive amines (histamine and serotonin)
Bradykinin
Complement cascade
Coagulation cascade and fibrinolytic system
Arachidonic acid metabolites (leukotrienes, prostaglandins, thromboxane A2)
Cytokines (Interleukins, TNF alpha)
What is the complement cascade?
-Component innate immune system
-Cascade of proteins that result in formation of MAC–> can destroy bacteria or recruit other cells
-Two main arms to complement cascade:
–> Classical: consists of antigen-antibody complexes
–> Alternative: activated by contact with micro-organisms
The complement cascade is a component of the innate immune system. It consists of a
cascade of proteins that result in the formation of a membrane attack complex, which can
destroy invading bacteria or recruit other cells to the inflammatory response.
There are two main arms to the complement cascade: the classic pathway consists of antigenantibody complexes. The alternative pathway is activated by contact with micro-organisms.
Note: Knowing the complement cascade in any more depth would be of no benefit as it will
not be tested further than this in part B.
What are the possible outcomes of acute inflammation?
Resolution
Progression to chronic inflammation
Organisation and repair culminating in scar formation
Death (meningitis is a good example)
Abscess formation (which may then drain spontaneously by means of a sinus)
Note: Remember the definitions.
An abscess is a collection of pus surrounded by granulation or fibrous tissue
A sinus is a blind-ended track lined by granulation tissue, which normally connects an abscess to the skin
What is a sinus?
A sinus is a blind-ended track lined by granulation tissue, which normally connects an abscess to the skin
What is an abscess?
An abscess is a collection of pus surrounded by granulation or fibrous tissue
What is chronic inflammation?
Chronic inflammation is present where there is:
-active inflammation
-tissue injury
-healing
at the same time.
defined by the cells types present (macrophages and lymphocytes)
and typically has a longer time course than acute inflammation
Can you name some examples of chronic inflammatory states
Persistent infection that evades host defence mechanisms e.g. TB, H. pylori
Endogenous agent e.g. gastric acid in PUD
Persistant or non-degradable toxin e.g. asbestos
Auto-immune diseases e.g. RA
Immunocompromise e.g. secondary to HIV or prolonged steroid use
What is a granuloma?
A granuloma is a collection of epithelioid macrophages.
What is granulomatous inflammation?
-Form of chronic inflammation characterised by presence of epithelioid macrophages
-Can fuse to form multinucleate giant cells (langerhan’s cells)
-These are sometimes present in granulomatous inflammation
Granulomatous inflammation is a form of chronic inflammation characterized by the
presence of epithelioid macrophages, called such as they resemble epithelial cells. These can
fuse to form multinucleate giant cells (Langhan’s cells) which are sometimes present in
granulomatous inflammation
How can granulomatous inflammation be classified and can you give some examples?
It can be classified as caseating (e.g. TB) or non-caseating (e.g. sarcoidosis, Crohn’s disease)
What is necrotising fasciitis?
-Aggressive infection that spreads from subcutaneous tissues to fascial planes
-Spreads rapidly along deep and superficial fascial planes, causing tissue necrosis
-Usually caused by synergistic polymicrobial infection (aerobes e.g. staph aureus, anaerobes e.g bacteroides)
-If monomicrobial usually due to haemolytic group A strep (strep pyogenes)
Nec fasc risk factors
-Diabetes
-Alcohol excess
-CKD
-Immunocompromise
