Diseases of the Respiratory System
Lu hua
Dept. of Pathology Three Gorges University Medical College
Emphysema
Definition
Emphysema is a condition of the lung characterized
by abnormal permanent enlargement of the airspaces
distal to the terminal bronchiole, accompanied by
destruction of their walls and without obvious fibrosis.
In contrast, the enlargement of airspaces unaccompanied
by destruction is termed "overinflation“.
Interstitial emphysema--is characterized by the entrance of air
into the connective tissue stroma of the lung, mediastinum, or
subcutaneous tissue . (rib fracture , penetrating injury of chest,
coughing plus some bronchiolar obstruction, etc.)
Compensatory emphysema-- the distention of airspaces that
occurs in the remaining lung parenchyma that follows surgical
removal of a diseased lung or lobe.
senile emphysema--For the elastic force of older pulmonary
tissue change to weakened, it make pulmonary residual volume
increased and cause lung expansion.
Obstructive Overinflation--Obstructive overinflation refers to
the condition in which the lung expands because air is trapped
within it. A common cause is subtotal obstruction by a tumor or
foreign object.
Types of true emphysema: four major types
•Centriacinar (Centrilobular ) emphysema
•The central or proximal parts of the acini, formed by respiratory
bronchioles, are affected, whereas distal alveoli are spared.
•Distal Acinar (Paraseptal) Emphysema
•The proximal portion of the acinus is normal, but the distal part is
predominantly involved.
•Panacinar (Panlobular) Emphysema
•The acini are uniformly enlarged from the level of the respiratory
bronchiole to the terminal blind alveoli
•Irregular Emphysema (Airspace Enlargement with
Fibrosis)
Irregular emphysema, so named because the acinus is
irregularly involved, is almost invariably associated with
scarring.
Thus, it may be the most common form of emphysema
because careful search of most lungs at autopsy shows
one or more scars from a healed inflammatory process.
In most instances, these foci of irregular emphysema are
often asymptomatic, clinically insignificant and only an
accidental autopsy finding.
Distal Acinar (Paraseptal) Emphysema
Centriacinar (Centrilobular ) emphysema
Pathogenesis: synergy of many factors
Two main factors:
1.Bronchial obstruction
2.The protease-antiprotease theory
1.Mild chronic inflammation throughout the airways,
parenchyma, and pulmonary vasculature
Damage of elastic fiber in
the wall of bronchiole and
alveolar wall.
Blood supply of the
alveolar interval reduce
Stenosis of bronchiole
Incomplete obstruction of
bronchiole
Dilatation of airspaces distal to
the terminal bronchiole
Damage of alveolar interval ,
it make alveolar interval
disappeared
Alveolar fusion to form
the bulla
 Inadequate ventilation
 Less perfusion
 Narrowed bronchiole
Destruction of alveolar walls
2.The protease-antiprotease theory
The most plausible hypothesis to account for the
destruction of alveolar walls is the protease-antiprotease
mechanism, aided and abetted by oxidant-antioxidant
imbalance.
The protease-antiprotease theory holds that alveolar
wall destruction results from an imbalance between
proteases (mainly elastase) and antiproteases in the
lung.
The protease-antiprotease imbalance and oxidant-antioxidant imbalance are
additive in their effects and contribute to tissue damage. α1-antitrypsin (α1AT) deficiency can be either congenital or "functional" as a result of oxidative
inactivation. (IL-8, interleukin 8; LTB4, leukotriene B4; TNF, tumor necrosis
factor.)
Morphology
•Enlargement
•Overinflation
•Brim blunt
circle
•Grey
•Low elasticity
Centriacinar emphysema. Central areas show marked
emphysematous damage (E), surrounded by relatively spared
alveolar spaces
Panacinar emphysema involving the entire pulmonary
architecture.
镜下：
Thin and stretched alveolar
walls
Spurs of broken septa
Distended alveoli and alveolar
duct
Inflammatory changes are
usually absent.
Clinical features: The clinical manifestations of
emphysema do not appear until at least one third of
the functioning pulmonary parenchyma is damaged.
Dyspnea----it is usually the first symptom; it begins
insidiously but is steadily progressive.
Cough and expectoration----these are extremely
variable and depend on the extent of the associated
bronchitis.
Weight loss— it is common and can be so severe as to
suggest a hidden malignant tumor.
Barrel-chested
Such patients may overventilate and remain
well oxygenated and therefore are somewhat
ingloriously designated as pink puffers (PP type).
Patients with chronic bronchitis more often have
a history of recurrent infection, abundant
purulent sputum, hypercapnia, and severe
hypoxemia, prompting the equally inglorious
designation of blue bloaters (BB type).
Predominant
Bronchitis(BB)
Predominant
Emphysema(PP)
Age (yr)
40-45
50-75
Dyspnea
Mild; late
Severe; early
Cough
Early; copious sputum
Late; scanty sputum
Infections
Common
Occasional
Respiratory
insufficiency
Repeated
Terminal
Cor pulmonale
Common
Rare; terminal
Airway resistance
Increased
Normal or slightly
increased
Elastic recoil
Normal
Low
Chest radiograph
Prominent vessels; large
heart
Hyperinflation; small
heart
Appearance
Blue bloater
Pink puffer
Death in most patients is due to
(1)Respiratory acidosis and coma
(2)Right-sided heart failure
(3)Massive collapse of the lungs secondary to
pneumothorax.
Bronchial Asthma
Asthma 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.
These symptoms are usually associated with widespread
but variable bronchoconstriction and airflow limitation
that is at least partly reversible, either spontaneously or
with treatment.
It is thought that inflammation causes an increase in
airway responsiveness (bronchospasm) to a variety of
stimuli.
Etiopathogenesis and types:
Typically, asthma is categorized into three types:
•Extrinsic (atopic, allergic) asthma —initiated by a
type I hypersensitivity reaction induced by exposure to
an extrinsic antigen
•Intrinsic (idiosyncratic, non-atopic) asthma —initiated
by diverse, nonimmune mechanisms, including
ingestion of aspirin; pulmonary infections, especially
viral; cold; inhaled irritants; stress; and exercise
•Mixed type —many patients do not clearly fit into
either of the above two categories and have mixed
features of both.
Morphology features:
Grossly;
Overdistended --the lungs are overdistended because
of overinflation, and there may be small areas of
atelectasis.
Mucous plugs --The most striking macroscopic
finding is occlusion of bronchi and bronchioles by
thick, tenacious mucous plugs.
Hyperinflated lungs of a patient who died with
status asthmaticus.
Mucous plugs
Basement membrane
Infiltration of eosnophils
Smooth muscle thickening
Mucous plugs
mucus
bronchial
cartilage
smooth
muscle
The bronchial lumen filled with mucus at the left
Submucosa is widened by smooth muscle hypertrophy, edema,
and inflammation (mainly eosinophils).
At high magnification, the numerous eosinophils are
prominent from their bright red cytoplasmic granules in
this case of bronchial asthma
Charcot-Leyden Crystals
The sputum usually contains numerous eosinophils and diamondshaped crystals (it formed by the fusion of the eosinophilic
particles derived from eosinophils).
The Spectrum of COPD
Clinical
Term
Anatomic
Site
Major Pathologic
Changes
Etiology
Signs/Symptom
s
Chronic Bronchus Mucous gland
bronchit
hyperplasia,
is
hypersecretion
Tobacco
smoke, air
pollutants
Cough, sputum
production
Bronchi
ectasis
Bronchus Airway dilation and
scarring
Persistent or
severe
infections
Cough,
purulent
sputum, fever
Asthma
Bronchus Smooth muscle
Immunologic
hyperplasia, excess
or undefined
mucus, inflammation causes
Emphys Acinus
ema
Airspace
enlargement; wall
destruction
Tobacco
smoke
Episodic
wheezing,
cough, dyspnea
Dyspnea