- Lung abscess is defined as necrosis of lung tissue forming cavities containing necrotic debris caused by microbial infection. It is most commonly caused by aspiration, necrotizing pneumonia, chronic pneumonia, or tuberculosis. - Symptoms include fever, cough, and shortness of breath. CT scan is the most sensitive imaging method and shows rounded cavities that may contain fluid or air-fluid levels with surrounding consolidation. - Treatment involves prolonged antibiotics and physiotherapy. Larger abscesses over 4cm have worse prognosis and sometimes require drainage procedures or surgery. Complications can include empyema or bronchopleural fistula.

1. Lung abscess
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Source:
http://radiopaedia.org/articles/lung-abscess
http://radiopaedia.org/articles/empyema-vs-pulmonary-abscess
http://emedicine.medscape.com/article/299425-overview
Lung abscess is defined as necrosis of the pulmonary tissue and formation of cavities
containing necrotic debris or fluid caused by microbial infection. The formation of multiple small
(< 2 cm) abscesses is occasionally referred to as necrotizing pneumonia or lung gangrene. Both
lung abscess and necrotizing pneumonia are manifestations of a similar pathologic process.
Failure to recognize and treat lung abscess is associated with poor clinical outcome.
Epidemiology
As a result of the widespread availability of antibiotics, the incidence of lung abscesses has dramatically
reduced. Similarly, mortality has reduced. The elderly, immunocompromised, malnourished, debilitated and of
course those who do not have access to antibiotics are particularly susceptible and have the worst prognosis 6
.
Particularly due to increased number of immunocompromised (secondary to HIV/AIDS and iatrogenic
immunosuppression) the rate has once more increased 7
.
Clinical presentation
Lung abscesses are divided according to their duration into acute (< 6 weeks) and chronic (> 6 weeks) 7
.
Presentation is usually non-specific and generally similar to a non-cavitating chest infection. Symptoms include
fever, cough and shortness of breath. Peripheral abscesses may also cause pleuritic chest pain 7
.
If chronic, symptoms are more indolent and include weight loss and constitutional symptoms. In some cases
erosion into a bronchial vessel may result in sudden and potentially life threatening massive haemoptysis.(ho ra
máu ồ ạt)
Pathology
It is convenient to divide lung abscesses into primary and secondary as they differ not only in aetiology, but
also microbiology and prognosis.(# diagnosis)
A primary abscess is one which develops as a result of primary infection of the lung. They most commonly
arise from (arise from:phát sinh do,nguyên nhân do)
Aspiration( Aspiration pneumonia)
necrotising pneumonia (viêm phổi hoại tử)
chronic pneumonia(viêm phổi mãn)
pulmonary tuberculosis(lao phổi)
In patients who develop abscesses as a result of aspiration, mixed infections are most common,
including anaerobes (vk kị khí).
Aspiration pneumonia is an inflammation of your lungs and bronchial tubes.
It happens after you inhale foreign matter. It is also known as

2. anaerobic pneumonia. This condition is caused by inhaling materials such as
vomit, food, or liquid.
Some organisms are particularly prone to causes significant necrotising pneumonia( viêm phổi hoại tử)
resulting in cavitation and abscess formation. These include 1
:
 Staphylococcus aureus
 Klebsiella sp: Klebsiella pneumonia
 Pseudomonas sp
 Proteus sp
In immunocompromised patients additional organisms may also be implicated including 7
:
Immunocompromised: im·mu·no·com·pro·mised (ĭm′yə-nō-kŏm′prə-m d ĭ-myoo′-)
Incapable of developing a normal immune response, usually as a result of disease, malnutrition, or immunosuppres
sive therapy.
Incapable of doing something: không thể làm được điều gì đó
Immunosuppressive: suppression of the immune response: drugs..
Response~ reaction.
 Candida albicans: pulmonary candidiasis
 Legionella micdadei & Legionella pneumophila
 Pneumocystis carinii (uncommon): pneumocystis jirovecii pneumonia
A secondary abscess is one which develops as a result of another condition. Examples include:
 bronchial obstruction: bronchogenic carcinoma, inhaled foreign body
 haematogeneous spread: bacterial endocarditis, IVDU
 direct extension from adjacent infection: mediastinum(trung thất), subphrenic(dưới cơ hoành), chest
wall(thành ngực)
Also sometimes grouped with secondary abscesses are colonisation of pre-existing cavities with
organisms 7
.
Radiographic features
As aspiration is the most common cause of pulmonary abscesses it is no surprise that the superior segment of
the right lower lobe (RLL)is the most common site of infection 6
.

3. =>Giải thích vì sao những dị vật thường rơi vào phế quản chính phải ??? có liên quan đến cấu trúc giải phẫu
của phổi

4. Plain film
The classical appearance of a pulmonary abscess is a cavity containing an air-fluid level. In general
abscesses are round in shape, and appear similar in both frontal and lateral projections(chuẩn đoán phân biệt
với tràn dịch-tràn khí màng phổi). Additionally all margins are equally well seen, although adjacent
consolidation may make assessment of this difficult. These features are helpful in distinguishing(phâm biệt) a
pulmonary abscess from an empyema (see empyema vs pulmonary
abscess)
CT
CT is the most sensitive and specific imaging modality to diagnose a lung abscess. Contrast should be
administered, as this enables the identification of the abscess margins, which can otherwise blend with
surrounding consolidated (bị đông đặc)lung.
Giải thích sự tạo thành surrounding consolidated lung? Trong lung abscess.
Abscesses vary in size, and are generally rounded in shape. The may contain only fluid or have an air-fluid
level. Typically there is surrounding consolidation, although with treatment the cavity will persist longer than
consolidation.

5. The wall of the abscess is typically thick and the luminal (sáng)surface irregular.
Bronchial vessels and bronchi can be traced as far as the wall of the abscess, whereupon they are
truncated( bị cụt)
Chụp cắt lớp điện toán ngực (CT scan ngực): giúp phân biệt áp xe phổi ngoại biên và mủ màng phổi khu
trú. Áp xe có bờ không đều, tạo góc nhọn ở màng phổi, không đẩy lệch mạch máu và phế quản, trong khí đó
mủ màng phổi có thành đều đặn, tạo góc tù với thành ngực, nhu mô phổi có thể bị đẩy. Ngoài ra, CT scan
ngực còn giúp nhận dạng ung thư phổi hoại tử
Phân biệt mủ màng phổi khu trú (empyema)và abscess phổi ngoại biên?
Empyema vs pulmonary abscess
Distinguishing between an empyema and a peripherally located pulmonary abscess is essential.
Lung abscesses are usually managed with prolonged antibiotics and physiotherapy with postural drainage
whereas an empyema usually requires percutaneous or surgical drainage.
Radiographic features
Plain film
 shape
o abscess is usually round in all projections
o an abscess may form a acute angle with the costal surface / chest wall
o empyema is usually lentiform(hình hột đậu)

6. CT
 relationship to adjacent bronchi / vessels
o abscesses will abruptly interrupt( làm gián đoạn) bronchovascular structures
o empyema will usually distort (bóp méo) and compress adjacent lung
 split pleura sign(dấu nứt màng phổi)
o thickening and separation(sự tách biệt) of visceral(tạng) and parietal pleura is a sign of
empyema
 wall
o abscesses have thick irregular walls
o empyema are usually smoother
 angle with pleura(tạo góc với màng phổi)
o abscesses usually have an acute angle (claw sign)-góc nhọn
o empyema have obtuse angles(góc tù)

7. empyema
Ultrasound
Ultrasound does not play a routine role in the assessment of lung abscesses as any aerated intervening lung
will prevent visualisation. Peripheral abscesses abutting the pleura or with only compressed or consolidated lung
may however be visible, and should not be mistaken for an empyema 4
. Consolidated lung may mimic a fluid
collection with low level echoes.
Treatment and prognosis(điều trị và tiên lượng)
Lung abscesses are usually managed with prolonged antibiotics and physiotherapy with postural drainage 2
.
Angiography: angio- , angi- (an'jē-ō, an'jē),
Denotes blood or lymph vessels; a covering, an enclosure; corresponds to L. vas-, vaso-, vasculo-.
[G. angeion, a vessel or cavity of the body]

8. Bronchoscopy may be beneficial in establishing bronchial patency to improve drainage 3
. In cases that are
refractory to conservative management, or those complicated by haemoptysis, empyema or suspected
malignancy( ác tính), surgical resection is the 'traditional' definitive treatment 5
. Percutaneous drainage under CT
guidance has also been advocated in selected cases 3
.
Larger abscesses (> 4 cm in diameter) are less likely(ít có khả năng) to be cured with medical
management only and have a higher mortality irrespective of treatment 3,6
.
irrespective /,iris'pektiv/+of treatment:tính từ (+ of) không kể bất chấp
Complications
Complications of surgery or percutaneous drainage include :
 empyema
 bronchopleural fistula (rò phế quản-màng phổi)
 haemorrhage (from chest wall or from lung)
Despite treatment abscesses continue to have high mortality (15-20%) 3, 6
. This is particularly the case in
nosocomial infections( nhiễm trùng bệnh viện), which account for the majority of deaths, presumably due to the
combined effect of pre-existent illness and higher prevalence virulent of antibiotic resistant strains,
particularly P. aeruginosa (mortality rate of 83%),S. aureus (50%) and Klebsiella pneumoniae (44%) 6
.
Differential diagnosis
General imaging differential considerations include
 empyema (see empyema vs pulmonary abscess)
 bronchogenic carcinoma (cavitating)
 pulmonary metastasis (di căn): with necrosis

9. Fig. 2. Chest X-ray of metastatic liver cancer. (A) Pre-treatment: Note numerous bilateral solid nodules,
and (B) Post-treatment: Note numerous bilateral pulmonary nodules that have decreased in size and density
(đông đúc) with associated cystic(nang) degeneration owing to (nhờ vào..)chemotherapy.
 pulmonary cavitating granulomatous disease (e.g granulomatosis with polyangiitis)
granulomas: granulum: little grain
 large infected pneumatocoele (
[G. pneuma, air, + kēlē, tumor, hernia]): infected emphysematous bulla
 cavitating pneumonia / necrotising pneumonia
Other considerations on plain film include
 pulmonary tuberculosis
 hiatus hernia (especially for a retrocardiac abscess)