Pulmonary infections

Dept. of Pathology

Three Gorges University Medical College

Lu Hua

•Pneumonia

•Abscess of lung

Pulmonary infections

Pneumonia(specific name)

Definition:

Acute exudative inflammation of lung

Three types:

•lobar pneumonia

•lobular pneumonia (bronchopneumonia)

•Interstitial pneumonia (viral and mycoplasmal pneumonia)

Type of pneumonia(The class are based on the area of changes)

1 、 lobular pneumonia

2 、 confluent bronchopneumonia

3 、 4 、 Interstitial pneumonia

5 、 lobar pneumonia

lobar pneumonia

• Definition:

lobar pneumonia is a widespread fibrinous consolidation of large areas and even whole lobes of the lung by acute bacterial infection.

lobar pneumonia• This pattern of acute bacterial

infection involves a large portion of lung or an entire lobe of lung.

• It is an acute fibrinous inflammation .

Etiology:• Most lobar pneumonias(90%) are

caused by pneumococci (type Ⅲ ), which enter the lungs via the airways.

• Other organisms: klebsiella , staphylococci, streptococci.

Etiology

Pneumonia can result whenever the defense mechanisms are impaired or whenever the resistance of the host in general in lowered e.g. catch cold 、 drunkenness and tiredness.

Etiology

•Defense mechanisms are impaired

•The Bacterium came into pulmonary alveolus

EtiologyThe Bacterium came into pulmonary alveolus

increasing

allergy

Vascular engorgement, serous fluid exude

Transudate with bacterium diffused via alveolar poreand involves a large portion of lung or an entire lobe of

lung.

Morphology

• Four stages of the inflammatory response include

• Congestion

• red hepatization

• gray hepatization

• resolution

Morphology

• Congestion– Predominates in the

first 24-48 hours.– The lung is heavy,

big and red.– Vascular

engorgement, intra-alveolar fluid with few neutrophils.

– Often presence of numerous bacteria.

Clinical course

Symptom of toxemia

1. shakes

2. hyperpyrexia

• Red hepatization (consolidation)– Predominates in the

3th–4th day – Describes lung tissue

with confluent acute exudation containing neutrophils and red cells, giving a red, firm, liver-like gross appearance.

Red hepatization

Red 、 firm

Red hepatization

Red hepatization

Clinical course

1. Rusty sputum (RBC disintegrate .)

2. Hypoxia

• Grey hepatization

– Predominates in the 5th-6th day

– Follows, as the red cells disintegrate and the remaining fibrinous exudate persists, giving a gray-brown gross appearance.

图 9-17 实变期 灰色肝样变期镜下改变

Grey hepatization

Clinical course1. White purulent sputum

• RBC disappeared

• Much fibrin

2.Hypoxia relieve .

• Alveolar pore are filled with exudation .

• Cavity of vessel are obliteration .

Morphology• Resolution

–The final stage –consolidated exudate undergoes

enzymatic digestion and cellular degradation and clearance.

– Normal structure is restored.

•The four stages is "classic" but infrequently seen because of antibiotic therapy.

•The injury of the alveolar wall usually don’t appear and the normal structure will be restored easily.

Complications

• Abscess formation

• Empyema(spread of infection to pleural cavity)

Complications

• Carnification: organization of exudate into fibrotic scar tissue (incomplete resolution).

• Bacteremia, septicemia and sepsis, with infection of other organs.

Carnification

Clinical course• The major symptoms: malaise,

fever, and cough productive of sputum. Pleuritic pain and pleural friction rub.

• The characteristic radiologic appearance: radiopaque well-circumscribed lobe.

lobular pneumonia (bronchopneumonia)

• This pattern of bacterial pneumonia is an acute purulent inflammation in lung parenchyma, caused most commonly by staphylococci, streptococci, pneumococci, and coliform bacteria.

lobular pneumonia

• It tends to occur in the more vulnerable two extremes of life --infancy and old age, particularly in those already suffering from some serious disorder.

• Grossly, the lungs show dispersed, elevated, focal areas of palpable consolidation and suppuration.

confluent bronchopneumonia

Morphology

• Histologic features consist of an acute (neutrophilic) suppurative exudate filling air spaces and airways, usually about bronchi and bronchioles.

4 、镜下：肺泡内大量中性粒细胞，少量红细胞，周围

肺组织充血、浆液渗出

Morphology

• Resolution of the exudate usually restores normal lung structure, but organization may occur and result in fibrous scarring in some cases, or aggressive disease may produce abscesses.

Clinical course

• 1. The major symptoms: fever, and cough productive of sputum. Abscess formation. Empyema.

• 2. The characteristic radiologic appearance: focal opacities.

typetype

featurefeaturelobar pneumonialobar pneumonia lobular pneumonialobular pneumonia

main targetmain target young adultsyoung adults childrenchildren 、、 elderly elderly peoplepeople 、、 Long illness Long illness who lie in bedwho lie in bed

pathogenesispathogenesis pneumococcuspneumococcus mixed infectionmixed infection

extentextent Lobe Lobe Lobule Lobule

charactercharacter fibrinous fibrinous inflammationinflammation

Purulent inflammationPurulent inflammation

clinical clinical featuresfeatures

Rusty sputumRusty sputum mucopurulent sputummucopurulent sputum

complicationcomplication Carnification heart failure, heart failure, bronchiectasisbronchiectasis

prognosisprognosis goodgood ，， most healmost heal badbad ，， most diemost die

Interstitial pneumonia

(viral and mycoplasma pneumonia)

Interstitial pneumonia

• Infections by viruses (e.g., influenza A or B, respiratory syncytial virus, adenovirus, rhinovirus, herpes simplex, cytomegalovirus) or mycoplasma pneumonic .

Morphology

• Grossly, patchy or lobar areas of congestion without the consolidation of bacterial pneumonias(hence the term "atypical" pneumonia).

Morphology

• 1. A predominance of interstitial with widened, edematous alveolar walls containing a mononuclear inflammatory cell infiltrate.

interstitial pneumonia. The alveolar septa are widened and edematous and infiltrated with mononuclear cells.

图 9-21 病毒肺炎（间质性肺炎）

The formation of hyaline membranes, reflecting diffuse alveolar damage.

Morphology

Morphology

• Certain viruses cause necrosis of bronchial or alveolar epithelium in severe infections (herpes simplex, adenovirus).

Morphology

Characteristic cytopathic changes are seen with some, e.g., giant cells and viral inclusion body in the cytomegalovirus infection.

viral inclusion body is round or oval shape, erythrocyte-like in size, eosinophilic cytoplasmic or nuclear

viral inclusion body

Clinical course

• The major symptoms: fever, headache, muscle aches.

• Low mortality rate(<1%) in the sporadic form and high mortality in epidemic form.

lung abscess

• It is a localised area of necrosis of lung tissue with

suppuration .

• It is a purulent inflammation of lung caused by

bacterium(Include anaerobe and aerobe)

• It is 2 types .

Types

• Primary lung abscess

• Secondary lung abscess

Primary pulmonary abscess

• The bacterium came into lung via the airway during the process of breath.

• Anaerobe (80%) is the main bacterium .• Usually have some cause e.g. resistance of

the host in lowered .

Secondary pulmonary abscess

• Some diseases of lung

• Foreign body obstruct the bronchi

• Spread of the purulent inflammation

of the adjacent organs to lung .

Morphology

•Abscess may be of variable size from a few millimeters to large cavities .5-6 cm in diameter .

•The cavity contains exudate .

Chronic lung abscess ： The cure of acute lung abscess is not thorough .(more than 3-6 months)

• Much necrotic tissue stay in vomica.• The thickness of the wall of vomica increased .• Bronchiole deform or the cavity expand .• Lymphocytes 、 plasma cells and macrophages .

Morphology

Morphology

• Bronchiole can be obstructed

• Liquefactive necrosis and vomica 。

• pleurisy

• empyema

Clinical course• suddenly ， chilly 、 hyperpyrexia(3

9 ～ 40 )℃ 。• cough 、 expectoration 、 chest

pain 、 breath lessness 。• Sputum :purulent 、 foul and with

much necrotic tissue .

• Emptysis