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

Etiology The Bacterium came into pulmonary alveolus increasing allergy Vascular engorgement, serous fluid exude Transudate with bacterium diffused via alveolar pore and 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 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

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 course 1.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.

type typefeature lobar pneumonia lobular pneumonia main target young adults children 、 elderly people 、 Long illness who lie in bed pathogenesispneumococcus mixed infection extentLobeLobule character fibrinous inflammation Purulent inflammation clinical features Rusty sputum mucopurulent sputum complicationCarnification heart failure, bronchiectasis prognosis good ， most heal bad ， most 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

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

Bronchiole can be obstructed Liquefactive necrosis and vomica 。 pleurisy empyema

Clinical course suddenly ， chilly 、 hyperpyrexia(39 ～ 40 ℃ ) 。 cough 、 expectoration 、 chest pain 、 breath lessness 。 Sputum :purulent 、 foul and with much necrotic tissue. Emptysis