Pathology Flashcards
what is oedema
excess watery fluid gathering in tissues/cavities
describe the pathology of pneumonia
infection involving the distal airspaces usually with inflammatory exudation, localised oedema
why does consolidation result from pneumonia
due to fluid present in air spaces
how is pneumonia classed by morphology
structure and form e.g. lobar pneumonia/bronchopneumonia
what is RSV
respiratory syncytial virus, can cause pneumonia
name 2 more viruses that can cause pneumonia
influenza, parainfluenza, measles
describe lobar pneumonia
confluent (flowing together or merging) consolidation involving a complete lung lobe
what is lobar pneumonia most commonly caused by
streptococcus pneumoniae
what transmits legionella
inhalation of vaporised stagnant water
is lobar pneumonia usually community or hospital acquired
community
describe the the acute inflammatory response associated with lobar pneumonia
exudation of fibrin-rich fluid, neutrophil infiltration, macrophage infiltration, resolution
what does the role of antigens lead to
opsonisation (serum molecules attach to microbes making them more attractive to antibodies- identification of pathogens by phagocytes that engulf them) and phagocytosis of bacteria
describe the pathology of meningitis
pus around the brain stem
what is edema
swelling- due to injury/inflammation, because of small blood vessels leaking in to tissue
what is an abscess a differential diagnosis of
cancer
what are the complications of lobar pneumonia
organisation (fibrous scarring), abscess, bronchiectasis, empyema
what is empyema
collection of pus in (pleural) cavity
what is a bronchopenuomia
infection starting in the airways and spreading to the adjacent alveolar lung
describe the pathology present in bronchopneumonia
patches of consolidation within the lung rather than the whole lung in lobar pneumonia
what (4) is bronchopneumonia usually a result of
COPD (exacerbation, acute bronchitis, hypoxic, resp failure), cardiac failure, complication of viral infection (influenza), aspiration of gastric contents (aspiration pneumonia)
what organisms commonly cause bronchopneumonia
more varied- strep. pneumoniae, haemophilus influenza, staphylococcus, anaerobes, coliforms (gut bacteria)
what microbes are common in aspiration pneumonia
staph., anaerobes, coliforms
what are the complications of bronchopneumonia
organisation, abscess, bronchiectasis, empyema
what symptoms of an abscess means its commonly misdiagnosed with cancer
chronic malaise (discomfort) and fever
what is an abscess
localised collection of pus
what is the tissue surrounding a tumour often like
haemorrhagic, inflamed and congested
what is bronchiectasis
abnormal fixed dilation of the bronchi
what is bronchiectasis usually due to
fibrous scarring following infection
give examples of infections/ conditions that result in infection that can cause fibrous scarring
pneumonia, tuberculosis, cystic fibrosis
how does scar tissue open airways
by contracting, dilates it
what does airway dilation do to the surrounding tissue?
destroys it
what results form the dilated airways
accumulation of purulent secretions, chronic suppuration, an inability to clear secretions
what is bronchiectasis also seen with
chronic obstruction (tumour)
what is tuberculosis
mycobacterial, chronic infection
how is tuberculosis pathology characterised
delayed type IV hypersensitivity (granulomas with necrosis)
describe hypersensitivity and what mediates it
t cell mediated, when own immune cells damage the body
what is a granuloma
localised collections of activated macrophages
what do organisms other than m. tuberculosis/ m. bovis cause
atypical infection especially in immunocomprimised host
what is pathogenicity
the ability of an organism to cause disease
describe the pathogenicity of organisms that cause tuberculosis
able to avoid phagocytosis- tough enzyme resistant coat, can stimulate a host T-cell response- hypersensitivity
what does the t-cell response to an organism enhance
macrophage ability to kill mycobacteria
what does t-cell response cause in hypersensitivity type IV
granulomatous inflammation, tissue necrosis and scarring
when does primary TB occur
1st exposure up to 5 years
describe the pathologocial process of gaining immunity against tuberculosis after inhalation of organism
organism phagocytosed and carried to hilar lymph nodes. immune activation (few weeks) leads to a granulomatous response in nodes (and in lung) usually with killing of organism
when does the infection spread within the body
when the infection is overwhelming or immune response impaired
what is secondary TB
reinfection or reactivation of TB in a person with some immunity
how does secondary tuberculosis tend to initially exist
remains localised, often shadows in apices of lung
how can secondary TB spread within the body
by airways or in bloodstream
what tissue changes occur in primary TB
small focus (Ghon focus) in periphery of mid zone of lung, granulomatous- large hilar nodes
what tissue changes occur in secondary TB
fibrosing and cavitating apical lesion, necrosis
what is a lesion
region of tissue that has suffered damage
is the organism killed in hypersensitivity
no
what does TB reactivate?
decreased T-cell function, reinfection at high does or with more virulent organism
what decreased T cell function
age, coincident disease (HIV- decreased T cell function T4H), immunosupressive therapy (steroids, cancer, chemotherapy)
when and how can TB reactivate
any stage in life with many manifestations
what pathogens/ infections affect an immunocompromised host
opportunistic pathogens- dont usually cause harm
virulent infections with common organisms
what is a lavage
washing out of body cavity
how is TB diagnosed
high index of suspicion (e.g. on treatment), multidisciplinary team, broncho-alveolar lavage, biopsy
how can TB cause a haemorrhage
infection spreads into blood vessel
how does HIV virus affect cells
swollen, enlarged nucleus due to viral particles
describe the dual supply of the pulmonary circulation
composed of pulmonary and bronchial arteries
is the pulmonary circulation a high or low pressure system
low
how are the pulmonary arteries able to act as a filter for the entire bloodstream
as pulmonary arteries receives entire cardiac output
because the pulmonary circulation is a low pressure system- at normal pressures- describe the vessels and incidence of atherosclerosis
thin walled vessels, low incidence of atherosclerosis
what is a pulmonary oedema
accumulation of fluid in the lung
describe interstitium oedema’s effect on patients
makes them breathless
describe oedema in the alveolar spaces
severe, causes consolidation
what are the two causes of pulmonary oedema
haemodynamic (increased hydrostatic pressure) cellular injury (alveolar lining and endothelium cells)
what causes localised cellular injury in the lungs
pneumonia
what causes generalised cellular injury in the lungs
adult respiratory distress syndrome
how does cardiac disease cause lung disease
as increases hydrostatic pressure
what is ARDS
adult respiratory distress syndrome
what is DADS
diffuse alveolar damage syndrome
what is shock lung
acute respiratory distress syndrome
what causes shock lung
sepsis, diffuse infection, severe trauma, oxygen treatment
describe the pathogenesis pf ARDS that leads to injury of cell membrane
inflammatory cells infiltrate lung, produce cytokines and oxygen free radicals
what pathological effects does ARDS have
fibrinous exudate lining alveolar walls (hyaline membranes), cellular regeneration, inflammation
what does a hyaline membrane do to alveolar lining
thickens it
what are three outcomes of ARDS
death, resolution, fibrosis (chronic restrictive lung disease)
what causes neonatal RDS
deficiency in surfactant causing physical damage to cells because of increased effort in expanding lung
what is an embolus
detached intravascular mass carried by the blood to a site in the body distant from its point of origin
what are most emboli
thrombi (clots)
what are 4 other types of embolus
gas, fat, foreign bodies, tumour clumps
what are pulmonary emboli an important cause of
sudden death and pulmonary hypertension
what is the source of most pulmonary emobli
DVT of lower limbs
what is a clot made of
platelets and fibrin
what does virchows trad show
risk factors for PE or DVT
what is virchows triad
factors in vessel wall, abnormal blood flow, hypercoaguable blood
what are the effects of a PE
sudden death, severe chest pain, dysnpnoea, haemopytsis, pulmonary infarction, pulmonary hypertension
what do the effects of a PE depend on
seize of embolus, cardiac function, respiratory function
what can be the effects of a small emboli
clinically silent, recurrent= pulmonary hypertension
what can be the effect of a large emboli
death, infarction, severe symptoms
what is ischaemic necrosis
death of tissue due to lack of blood supply (pulmonary infarct)
what is secondary pulmonary hypertension almost always due to
lung disease
how does hypoxia cause pulmonary hypertension
as causes vascular constriction ONLY IN THE LUNG- EVERYWHERE ELSE HYPOXIA CAUSES DILATION
how does congenital heart disease cause pulmonary hypertension
as increases flow through pulmonary vascular bed
how does a PE or emphysema cause pulmonary hypertension
blackage (PE) or loss (emphysema) of pulmonary vascular bed (blood vessels of the lungs)
what type of heart failure can cause pulmonary hypertension
left sided heart faiure- back pressure
describe the hypertrophy present in pulmonary hypertension
right ventricular hypertrophy, medial hypertrophy of arteries
what are two other factors of the morphology of pulmonary hypertension
intimal thickening (firbrosis), atheroma (fatty material that forms deposits in arteries)
what causes the thickening of pulmonary arteries in pulmonary hypertension and what is it called
caused by muscular fibrosis and pulmonary hypertension. called intimal fibrosis
what is cor pulmonale
pulmonary hypertension complicating lung disease
what are the three components of cor pulmonale
right ventricular hypertrophy, right ventricular dilatation, right heart failure
what is the pleura
a mesothelial (lubricated) surface lining the lungs and the mediastinum
what is a pleural effusion
accumulation of fluid in the pleural cavity
is transudate or exudate low or high in protein
transudate low protein
exudate high protein
what type of process is transudate and what causes it
passive process= cardiac failure, hypoproteinaemia
what type of process is exudate and what causes it
inflammatory process due to; pneumonia, TB, connective tissue disease, malignancy
give an example of when a purulent pleural effusion
empyema
what causes a effusion to be purulent
when its full of acute inflammatory cells
what is a pneumothorax and what can cause it
air in pleural space caused by trauma or rupture of bulla (blister)
what causes a spontaneous pneumothorax
rupture of bulla
what are the two types of primary pleural neoplasia
benign (rare), malignant mesothelioma
what is a common form of secondary pleural neoplasia
adenocarcinomas
can you get benign mesothelioma
no
why can mesothelioma look like either sarcoma or carcinoma
mixed epithelial/mesenchymal differentiation
