pathology of the respiratory system 2
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Systemic pathologyTRANSCRIPT
PATHOLOGY OF THE RESPIRATORY SYSTEM
BY
CHAPIMA F.MSc. PTH - Clinical Pathology (UNZA), B.Sc. (UNZA)
Lecture outline Normal lung Pathology
Congenital anomalies of the lung Atelectasis Obstructive pulmonary diseases Restrictive pulmonary diseases Pulmonary infections Lung tumours
CONGENITAL DISORDERS Congenital anomalies of the lungs commonly
present within the first 2 years of life and frequently manifest with respiratory distress and cyanosis
1. Laryngeal Web This is the partial opening of the larynx. A membranous web forms at the level of the
vocal cords, partially obstructing the airways.
2. Laryngotracheal stenosis/Atresia
Laryngotracheal stenosis refers to abnormal
narrowing of the central air passageways.
This can occur at the level of the larynx,
trachea, carina or main bronchi.
Rare
Usually associated with some
tracheoesophageal fistula.
3. Pulmonary Sequestration
Pulmonary Sequestration is the presence of a
lung tissue not connected to the airway system.
It can be located in the thorax or
mediastinum
Its blood supply comes directly from the aorta or
its branches and not from the pulmonary
arteries.
Pulmonary Sequestration……….
Types
2 types are noted
Intralobar Sequestration – the lung tissue is
enclosed within the pleura of the normal lung.
Usually it is located in the lower lobes and
60% on the left lung.
Pulmonary Sequestration………..
Extra lobar Sequestration
The lung tissue is separated from the pleural
covering.
May be found anywhere in the thorax or
mediastinum and they are associated with
polyhydramnios
ATELECTASIS (LUNG COLLAPSE)
Definition:
AKA collapsed lung refers to the collapse of a
previously expanded lung tissue.
Major types
It is classified according to the cause;
Obstructive Atelectasis
Compression Atelectasis
Contraction (Scar) Atelectasis
Atelectasis………..
Obstructive
Atelectasis occurs
when an obstruction
prevents air from
reaching distal airways
e.g. aspiration of a
foreign body.
Atelectasis………..
Compression
Atelectasis
Due to fluid, air, blood,
or tumor in the pleural
space Compression Atelectasis
Atelectasis………..
Contraction (Scar)
Atelectasis
Occurs when there is either
local or generalized fibrotic
changes in the lung or pleura
which hampers expansion of
the lung during expiration.
Atelectasis………..
All types of Atelectasis (except contraction) are
potentially reversible.
The best treatment is to treat the cause.
CHRONIC OBSTRUCTIVE PULMONARYDISEASE
COPD is a group of lung diseases that makes it
hard to breathe out.
Three major diseases are encountered in clinical
situations:
Chronic Bronchitis
Emphysema
And Asthma
1. Chronic bronchitis
Definition
Defined clinically as a productive cough for at
least 3 consecutive months for at least 2
consecutive years.
Highly associated with cigarette smoking
(90%) and air pollution.
Etiopathogenesis………..
Cigarette Smoking affects the lung in a number of ways;
1. It impairs ciliary movement.
2. It inhibits the function of alveolar macrophages.
3. It leads to hypertrophy and hyperplasia of mucus secreting glands as a result there is increased secretion of mucus which leads to obstruction of small airways.
Etiopathogenesis………..4. It also stimulates the Vagus nerve and causes
bronchoconstrictionClinical findings Persistent productive cough of long duration Dyspnea more on exertion Cyanosis Edema Chest painsPulmonary function tests show; Increased pulmonary resistance Reduced expiratory flow rates
Gross Morphologic features
The bronchial wall is
thickened, hyperemic and
edematous.
Lumina of the bronchi and
bronchioles may contain
mucus plugs and purulent
exudate.
Complications
Recurrent chest infections
Pulmonary HTN leading to right heart failure
(cor-pulmonale)
Lung cancer
2. Emphysema
Definition
Is an abnormal permanent enlargement of the
airspaces distal to the terminal bronchiole,
accompanied by destruction of their walls.
Classifications
Emphysema is classified according to its
anatomic distribution within the lobule.
Classifications………..
Four major types of emphysema exists but
only the first two cause clinically significant
airway obstruction.:
Centroacinar Emphysema: Dilation is limited
to the central or proximal parts of the acini.
Panacinar emphysema: there is dilatation of
the entire acinus.
Classifications…………..
Classifications……………
Distal acinar emphysema: Dilation involves
mainly the distal part of the acinus.
Irregular emphysema: the acinus is irregularly
involved and is usually a complication of various
inflammatory processes.
Pathophysiology
Emphysema depends on the balance between
proteolytic enzymes, such as elastase and
antiproteinase-antielastase activities of α1-
antitrypsin.
Elastase if not neutralized by anti-elastase
will induces destruction of elastin causing
emphysema.
Pathophysiology …………..
Cigarette smoking causes emphysema by
attracting neutrophils and macrophages,
which are sources of elastase.
It also inactivates α1-antitrypsin.
Morphology
Cut surface of the lung shows distended air
spaces in the lobules.
Morphology…………….
Morphology…………….
Morphology…………….
Microscopic
There is distension and
destruction of the respiratory
bronchiole in the lobules
surrounded peripherally by
normal uninvolved alveoli.
Clinical features
Progressive dyspnea
Scant sputum production
Increased total lung capacity: due to increase in
residual volume from air trapped in the lungs
and Decreased FEV
Complications
Chronic bronchitis.
Pneumothorax due to the rupture of a surface
bleb.
3. Bronchial asthma
Definition
This is a Chronic Inflammatory disorder of the
airways that causes recurrent episodes of
wheezing, breathlessness, chest tightness, and
cough, particularly at night and/or in the early
morning.
Types
Extrinsic (immune, atopic or allergic)
asthma.
Disease begins in childhood, usually in patients
with a family history of allergy
Types……….
Intrinsic (non-immune, non-atopic) Asthma
or adult type) asthma includes asthma
associated with chronic bronchitis, as well as
other asthmas induced by exercise - or cold-
induced.
It usually begins in adult life and is not
associated with a history of allergy.
Types…………
Mixed asthma, which has characteristics of
allergic and idiopathic asthma.
Mixed asthma is the most common form.
Pathophysiology
The pathophysiology of bronchial asthmatic
attack is related to the release of chemical
mediators in an IgE and mast cell interaction.
When the antigen enters the air ways, IgE are
produced against these antigens which binds or
interacts with mast cells.
The mast cells ruptures and release chemical
mediators such as histamine.
Pathophysiology …………
The release of histamine results in:- Bronchospasm (rhythmic squeezing of the
airway). Production of abnormal amount of thick
mucus and initiates Inflammatory response, including increased
capillary permeability and mucosal edema.
Pathophysiology …………..
Narrowing of the air ways leads to;
Difficulty of expiratory phase of respiration
Retention of expired air in the alveoli & lung -
hyper inflation.
Signs and symptoms
Dyspnea
Wheezing on expiration caused by narrowing of
the airways.
Complications
Status asthmaticus
Superimposed chest infections
Chronic bronchitis
Emphysema
Death can result
RESTRICTIVE PULMONARY DISEASES
Restrictive pulmonary diseases are
abnormal conditions that are characterized by
reduced expansion of the lung and reduction in
total lung capacity.
It leads to difficulties in the inspiratory phase of
respiration.
Restrictive lung diseases…………
Restrictive lung diseases can be due to;
Chest wall disorders.
Interstitial and infiltrative lung diseases.
Restriction due to chest wall disorder
Kyphosis, Poliomyelitis
Pleural diseases
Restriction due to interstitial and infiltrative lung diseases
AKA interstitial lung diseases (ILDs), these are
diseases characterized by non-infectious lung
diseases.
They are referred to as Pneumoconiosis.
Pneumoconiosis
It is an environmental disease caused by inhalation of inorganic dust particles.
They are characterized by permanent retention of inhaled particles, which results in inflammation and fibrosis of the lung.
The major conditions include; Silicosis due to silica dust inhalation Asbestosis due to inhalation of asbestos fibers Anthracosis due to carbon inhalation
1. Anthracosis
Anthracosis is caused by
inhalation of carbon dust.
It results in irregular black
patches visible on gross
inspection.
It is common in urban areas
and causes no harm.
2. Silicosis
Silicosis is a chronic
occupational lung
disease caused by
exposure to free silica
dust
It is seen in miners,
glass manufacturers,
and stone cutters.
Advanced silicosis Scarring has contracted the upper lobe into a small dark
mass (arrow). Note the dense pleural thickening.
3. Asbestosis
Asbestosis is caused by inhalation of asbestos
fibers.
This disease is initiated by uptake of asbestos
fibers by alveolar macrophages.
A fibro-blastic response occurs from the release
of fibroblast-stimulating growth factors by
macrophages.
Asbestosis…………
This leads to diffuse
interstitial fibrosis, mainly in
the lower lobes.
Asbestosis results in marked
predisposition to
bronchogenic carcinoma.
Asbestos-related pleural plaques. Large, discrete fibrocalcific plaques are
seen on the pleural surface of the diaphragm.
PULMONARY INFECTIONS
1. PNEUMONIA Pneumonia is an inflammation of the lung
parenchyma.
It is characterized by; Chills and fever Productive cough Blood-tinged or rusty sputum Chest pains - Pleuritic in nature Shortness of breath and cyanosis
Classifications
Pneumonia is classified according to the cause
or morphologically.
According to the cause it can be;
Bacterial pneumonia
Streptococcus pneumoniae
Staphylococcus aureus
Klebsiella pneumonia
Classifications…………….
Pseudomonas aeruginosa
Viral pneumonias with Haemophilus influenza
especially type A as the usual causative
organism.
Fungal pneumonia - Pneumocystis jiroveci
(carinii) pneumonia is the most common
opportunistic infection in patients with AIDS.
Classifications…………….
Morphologically it can be classified as;
Lobar pneumonia
Bronchopneumonia or
Interstitial pneumonia
Lobar pneumonia
Lobar pneumonia is an acute
bacterial infection of a part of a
lobe, the entire lobe, or even two
lobes of one or both the lungs.
Causative organisms
Streptococcus pneumoniae more than 90% of all
lobar pneumonias
The other 10% may be caused by;
Staphylococcus aureus
β-hemolytic streptococci
Haemophilus influenza
Klebsiella pneumoniae
Morphological stages
If untreated, may follow 4 morphological
stages:
Congestion
Red hepatization
Gray hepatization and
Resolution
Morphological stages…………..
Congestion
This is the initial phase.
It represents the early acute
inflammatory response to
bacterial infection and lasts for
1 to 2 days.
Lungs are dark, red and wet.
Morphological stages…………..
Red hepatization
The term hepatization refers to liver-like consistency of the affected lobe on cut section.
This phase lasts for 2 to 4 days.
Lungs are solid, red and dry.
Morphological stages…………..
Gray hepatization
This phase lasts for 4 to 8
days.
The lungs are solid and
grey due to high
concentration of neutrophils in
the affected lung.
Morphological stages…………..
Resolution This stage begins by 8th to 9th day if no
treatment is given and is completed in 1 to 3 weeks.
However, antibiotic therapy induces resolution on about 3rd day.
The previously solid fibrinous constituent is liquefied by enzymatic action, eventually restoring the normal ventilation in the affected lobe.
Complications
Pleural effusion
Empyema
Lung abscess
Metastatic infection
Septicaemia
Bronchopneumonia
Bronchopneumonia is caused
by a wide variety of organisms.
It is characterized by
consolidated areas of acute
suppurative inflammation.
Bronchopneumonia……..
Interstitial pneumonia
Interstitial (primary atypical) pneumonia is
caused by various infectious agents, most
commonly Mycoplasma pneumoniae or
viruses.
It is characterized by diffuse, patchy
inflammation localized to interstitial areas of
alveolar walls.
2. LUNG ABSCESS
This is a localized area of suppuration within the
parenchyma.
Predisposing factors
Aspiration of micro-organisms due to loss of
consciousness from alcohol or drug overdose
Infections e.g. pneumonia
Clinical manifestations
Includes;
Fever, chest pains
Productive cough with a foul-
smelling purulent sputum
Radiographic evidence of a
fluid-filled cavity.
Cut surface – abscess seen
3. PULMONARY TUBERCULOSIS
Definition - It is an infection of the lung with
Tubercle bacilli.
it is spread by inhalation of droplets containing
the organism tubercle bacillus (also referred to
as the Mycobacterium tuberculosis).
Classifications
Primary tuberculosis is the initial infection,
characterized by the primary, or Ghon complex
(The lesions consist of a calcified focus of
infection and the hilar lymph nodes).
Secondary tuberculosis usually results from
activation of a prior Ghon complex, with spread
to a new pulmonary or extrapulmonary site.
Clinical features
Include;
Coughing
Chest pains
Fever
Hemoptysis
Pleural effusion and generalized wasting
Pathologic changes
Localized lesions usually in the apical or
posterior segments of the upper lobes.
Involvement of hilar lymph nodes is also
common.
Tubercle formation - The lesions frequently
coalesce and rupture into the bronchi.
Pathologic changes ………..
The caseous contents may liquefy and be
expelled, resulting in cavitary lesions.
Cavitation is a characteristic of secondary, but
not primary, tuberculosis; caseation (a
manifestation of partial immunity) is seen in
both.
Scarring and calcification
Primary pulmonary tuberculosis, Ghon complexThe gray-white parenchymal focus is under the pleura in the
lower part of the upper lobe. Hilar lymph nodes with caseation are seen on the left.
Milliary TB
LUNG CANCER
Definition
Malignant tumors of the lung’
Epidemiology
Rate of increase in lung cancer is declining in
men but increasing in women: peak incidence is
55-65 years of age.
Classifications
Most lung tumors are malignant.
LC can be classified as;
1. Primary lung cancer
2. Secondary lung cancer (metastatic cancer)
Metastatic cancer - is the most frequent lung
cancer than primary lung cancer.
Classifications ……………
For therapeutic purposes, primary
carcinomas are subdivided into;
Non-small cell carcinoma (75% of cases)
Small cell carcinoma (20% of cases)
Non-small cell carcinomas usually respond to
surgery
Whereas small cell carcinomas are usually
inoperable.
Predisposing factors
Cigarette smoking – it is directly proportional in incidence to the number of cigarettes smoked daily and to the number of years of smoking.
Other factors; Air pollution Radiation; incidence increased in radium and
uranium workers Asbestosis Industrial exposure to nickel
Clinical findings
Cough: most common symptom
Dyspnea
Hemoptysis
Weight loss
Chest pain
Gross Morphology
Sites of metastasis of primary cancer
Adrenal gland
Liver
Brain
Bone
References
Emanuel Rubin, and John L. Farber, Essential Pathology, Philadelphia,
1990
William Boyd; Textbook of Pathology, structure and Function in disease,
Philadelphia, 8th edition, 1987
Macfarlane, Reid, Callander, Illustrated Pathology, Churchill
Livingstone, 5th edition, 2000.
Cotran RS, Kumar V, Collins T. Robins pathologic basis of diseases.
Philadelphia, J.B. Saunders Company. 6th edition. 1999
Muir’s Textbook of Pathology 15th edition