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PneumoniaBy Dr. Abdelaty Shawky Assistant professor of pathology

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PNEUMONITIS

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* Classification: 1. Bacterial pneumonia: lobar pneumonia & bronchopneumonia. 2. Viral (interstitial) pneumonia: influenza, measles, chicken pox. 3. Loefflers (parasitic) pneumonia: Bilharziasis, ascaris & ankylostomiasis. 4. Granulomatous pneumonia: T.B, sarcoidosis, leprosy, syphilis, actinomycosis. 5. Lipoid pneumonia: due to aspiration of oily nasal drops. 6. Irradiation pneumonia.

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LOBAR PNEUMONIA

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* Def: acute diffuse fibrinous inflammation of one or more lung lobes. * Etiology: Age: middle age. Predisposing factors: low resistance. Causative organism: pneumococci. Route of infection: droplet infection.

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* Pathogenesis: Pneumococci are inhaled to reach alveoli. They cause acute inflammaion with excess fluid exudate. This fluid exudate pass from one alveolus to another rapidly through the inter- alveolar pores of cohn to involve the whole lung lobe. The fluid exudate expel air away from the alveoli producing a firm airless lobe leading to consolidation (hepatisation) of the affected lobe.

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4. Stage of resolution 3. Stage of gray hepatization 2. Stage of red hepatization 1. Stage of congestion 1. Duration 9th day 215th 8th day2nd 4th day1st day 2. Gross Picture: the affected lobe is - Since there is no necrosis, healing by resolution occurs. - Enlarghed. - Gray. - Consistency: consolidated (hepatized). - Cut section: dry. - Pleurisy. - Enlarged hilar LNs. - Enlarged. - Red. - Consistency: consolidated (hepatized). - Cut section: dry. - Pleurisy. - Enlarged hilar LNs. - Size: Enlarged. - Color: Red. - Consistency: like wet sponge. - Cut section: exudes frothy fluid. - The covering pleura: normal - The hilar L.Ns.: normal

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Lobar pneumonia of upper lobe

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Lobar pneumonia of the lower lobe

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4. Stage of resolution 3. Stage of gray hepatization 2. Stage of red hepatization 1. Stage of congestion 3. Microscopic Picture a. Alveolar capillaries: Less congested b. Alveolar walls: thin. c. Alveolar spaces: Show dead bacteria, shrinked fibrin, hemolysed RBCs, excess polymorphs and macrophages. a. Alveolar capillaries: Congested. b. Alveolar walls: thickened. c. Alveolar spaces: Show bacteria, fibrin, RBCs and polymorphs. a. Alveolar capillaries: Congested. b. Alveolar walls: thickened. c. Alveolar spaces: Show bacteria & fluid exudate.

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Lobar pneumonia; red hepatization

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Lobar pneumonia; grey hepatization

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4. Stage of resolution 3. Stage of gray hepatization 2. Stage of red hepatization 1. Stage of congestion 4. Clinical course - Fever, cough, dyspnea and chest pain. - At about 9th day the disease ends by crisis (sudden improvement), however death may occur due to severe toxaemia.

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4. Stage of resolution 3. Stage of gray hepatization 2. Stage of red hepatization 1. Stage of congestion 5. Complications 1. Spread of infection: direct, lymphatic and blood (toxaemia, septicaemia). 2. Lung fibrosis due to failure of resolution. 3. Post-pneumonic lung abscess.

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BRONCHOPNEUMONIA

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* Def: Acute suppurative inflammation of bronchioles and adjacent alveoli characterized by patchy lung consolidation. * Etilogy: Age: extremes of age (young & elderly). Predisposing factors: low resistance and bronchitis. Causative bacteria: staphylococci, streptococci & H. influenza. Route of infection: endogenous invaders and exogenous invaders (droplet infection).

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* Gross picture: Bilateral. Basal. Multiple consolidated yellowish patches exuding pus on pressure. Several patches may coalesce to produce confluent bronchopneuomonia. Enlarged hilar L. nodes.

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Bronchopneumonia

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Bronchopneumonia

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* Microscopic Picture: I. The broncioles show: Their lumen shows: necrotic epithelial cells, polymorphs & pus cells. Their lining: ulceration. Their walls: congested capillaries, neutrophils and pus cells & exudate. II. The adjacent alveoli show: 3 successive zones: zone of alveolitis then zone of alveolar collapse and a zone of alveolar dilatation (compensatory emphysema).

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* Complications: 1. Spread of infection: direct, lymphatic and blood (toxaemia, septicaemia). 2. Lung fibrosis due to failure of resolution. 3. Post-pneumonic lung abscess. 4. Bronchiectasis.

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Thanks