Viral Pneumoni Dari 18

8/11/2019 Viral Pneumoni Dari 18

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Gambaran radiologis pneumonia virus secara umum

Clinically, viral pneumonia in adults can be divided into two groups: so-called atypical

pneumonia in otherwise healthy hosts and viral pneumonia in immunocompromised hosts ( 5 )

Infl uenza virus types A and B account for most viral pneumonias in immunocompetent

adults ( 5 ). It has been considered that clinical history,

results of physical examination,

and imaging features cannot enable the

prediction of the etiologic agent.

--

Various histopathologic patterns of

lung injury have been described in viral

pneumonia. Although some of these

patterns may be relatively unique to a

specifi c clinical context, others are nonspecifi

c with respect to either the cause

or pathogenesis.

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Viruses can result in several pathologic

forms of lower respiratory tract

infection, including tracheobronchitis,

bronchiolitis, and pneumonia.

--


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Most respiratory viruses damage cells

directly through cytopathic effects mediated

by means of either viral-directed

cell lysis or the inhibition of host cell

RNA, protein, and DNA synthesis. Other

viruses (eg, cytomegalovirus [CMV], adenovirus,

or herpesvirus) may produce

specifi c nuclear changes or characteristic

cytoplasmic inclusions ( 11 ) ( Fig 1 ).

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Cytopathic respiratory viruses (eg,

infl uenza, adenovirus, and herpesvirus

group) cause a virus-specifi c lung injury

pattern. Infl uenza virus affects the epithelium

diffusely and, in severe cases, results

in necrotizing bronchitis and/or bronchiolitis

and diffuse alveolar damage.

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The histologic features of infl uenza

pneumonia are epithelial necrosis of the

airways with submucosal chronic infl ammation.


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Fatal infl uenza pneumonia represents

a necrotizing bronchiolitis with

diffuse alveolar damage, which can be

hemorrhagic.

Adenovirus has its greatest effect in

the terminal bronchioles and may produce

bronchiolitis or even bronchiectasis

( 1214 ). The bronchiolitis may be necrotizing

and result in a necrotizing bronchopneumonia

similar to that seen in severe

herpes simplex infection ( 13 ) ( Fig 2 ).

--

In immunocompetent individuals,

RSV and parainfl uenza viruses may produce

necrotizing bronchiolitis characterized

by exudates within bronchiolar

lumen, infl ammatory cells in the wall

of bronchioles, a peribronchiolar reaction

with chronic infl ammatory cells, and

exudate in alveoli. In immunocompromised

patients, parainfl uenza viruses


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produce giant cell pneumonia with diffuse

alveolar damage indistinguishable

from that caused by measles pneumonia.

--

The predominant pathologic process

of hantavirus pulmonary syndrome and

severe acute respiratory syndrome (SARS)

is diffuse alveolar damage and diffuse

lung disease characterized histologically

by interstitial edema and central alveolar

fi lling ( 18 , 19 ) ( Fig 5 ).

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The radiologic fi ndings refl ect the

variable extent of the histopathologic

features, which include diffuse alveolar

damage (intraalveolar edema, fi brin,

and variable cellular infi ltrates with a

hyaline membrane), intraalveolar hemorrhage,

and interstitial (intrapulmonary

or airway) infl ammatory cell infi ltration

( 20 ).


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Manifestasi klinik infeksi virus

The clinical signs and symptoms of viral

pneumonia are often nonspecifi c, and

the clinical course of infection will be

highly dependent on the overall immune

status of the host ( 3 ).

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The possibility of pneumonia should

be considered in any patient who has new

respiratory symptoms (including cough,

sputum, or dyspnea), particularly when

these symptoms are accompanied by fever

or abnormalities at physical examination

of the chest (eg, rhonchi and rales).

--

Pneumonia is also increasingly prevalent

in patients with specifi c comorbidities

or risk factors, including smoking,

chronic obstructive pulmonary disease,

asthma, diabetes mellitus, malignancy,


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heart failure, neurologic diseases, narcotic

and alcohol use, and chronic liver

disease.

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A thorough physical examination, posteroanterior

and lateral chest radiography,

and a blood leukocyte count with

a differential cell count should be performed

when pneumonia is suspected.

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Even with intensive laboratory investigation,

the specifi c microbiologic cause can be established with certainty

only in approximately 50% of patients

with pneumonia. The probable predominant

organism varies with the hosts epidemiologic

factors, the severity of illness,

and the laboratory approach used to establish

the diagnosis.

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Although most attention traditionally

focuses on bacterial causes of severe


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community-acquired pneumonia, viruses

can also cause serious lower respiratory

tract infections. The predominant respiratory

viruses that can cause severe

pneumonia include infl uenza and RSV

Viral Pneumoni Dari 18

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