Pulmonary tuberculosis (PT):
- Common lung infection worldwid.
- Epidemic in mediterranean countries.
- Long,
well-defined treatment that different from other bacterial infections: his specific diagnosis is very important.
Its clinical form of presentation is insidious and early diagnosis is often difficult if the process is not suspected on radiological findings.
Clinically
- Systemic manifestations including fever,
malaise and weight loss.
The fever is not very high and is usually well tolerated.
Other common clinical features are cough,
hemoptoic expectoration or hemoptisis.
- In our serie,
revelator symptoms were nonspecific and variable.
Radiological features
- Considerable variation,
but in most cases they are characteristic enough to suggest the diagnosis.
- Chest radiography results are frequently sufficient for the diagnosis
- In our serie,
chest radiography was performed in all 135 cases.
In concordance with the literature data,
it was sufficient for tuberculosis diagnosis in most cases guided by the clinical and laboratory data.
- CT provides diagnostic findings in cases where the chest radiograph is normal or inconclusiv.
- It was performed in 22 of our 135 patient.
- Classically,
tuberculosis is divided in two forms: primary (PT) and postprimary (PPT).
These groups not only represent clinically different processes,
but also different radiological presentations.
Primary tuberculosis (PT)
- Often misdiagnosed,
asymptomatic.
- In our country,
since antituberculous vaccination is systematic at birth,
it is impossible to really differentiate between a PT and PPT and these two entities are often confused.
- The most characteristic radiological feature in primary tuberculosis is:
- lymphadenopathy,
which is observed in almost all patients.
Generally unilateral,
with the hilar and paratracheal regions most often affected and less frequently the subcarinal nodes.
- Parenchymal consolidation is a common associated feature,
but lymphadenopathy is often the only radiological finding
CT is more sensitive than plain films for the detection of lung lesions and enlarged lymph nodes.
Postprimary tuberculosis (PPT)
- Reactivation of a previous tuberculous lesion: chronic granulomatous infection
- Histology: caseation necrosis
- Radiologically,
PPT manifests as
- Consolidation: patchy,
poorly defined segmental.
Mainly apical and posterior segments of the upper lobes
less frequently in the superior segment of the lower lobe (typical distribution: high concentration of oxygen in the upper lung areas,
increased virulence of the bacilli,
and less effective lymphatic drainage of these segments as compared to other areas of the lung)
- Cavitation: characteristic of PPT.
Appears in around half of patients.
They may be single or multiple
In our serie,
cavitation was found in 57 patients (42.2%).
They were right in 35 cases,
left in 25 cases and bilateral in 9 cases
Usually have thick walls with irregular margins
Air-fluid level: possible.
12 air fluid levels were found in our serie.
- Nodular opacities: associated with the cavitations or alone
- “tree-in-bud”pattern: consisting of multiple branching linear structures (bronchogenic dissemination of the disease)
In our serie,
this pattern was found in 13 cases (59%)
Tree-in-bud opacities are also seen in other infections,
but when visualized in combination with cavitations or nodular opacities in the upper and posterior lung segments and in the appropriate clinical setting,
a specific diagnosis of pulmonary tuberculosis can be established.
- hilar and mediastinal lymphadenopathy is uncommon.
- Tuberculous pleurisy is more common in primary than post primary disease.
In our serie,
there was 12 pleurisy
Miliary disease
- Widespread dissemination of tuberculosis by hematogenous spread.
- Can occur in both primary and postprimary tuberculosis.
- Commonly seen in the elderly and immunocompromised patients.
- In our serie this feature was seen with 4 patients,
without immunodeficiency.
- Multiple diffuse nodules,
1- 3mm in size
- Chest plain films provide diagnostic features in most cases,
but late in the evolution.
- CT: accurate early diagnosis: randomly distributed micronodular pattern.
- This type of random distribution is also observed in hematogenous.
Differentiel diagnosis: metastatique miliary,
but the nodules are
larger.
Active versus inactive lesions
- Chest plain films have limited value for this purpose,
since they can only establish that the lesion is stable,
and stable lesions can contain active bacilli.
- CT can add valuable information for the detection of activity
Branching opacities,
cavitations or consolidation are clear signs of active tuberculosis
Conclusions
The spectrum of radiologic manifestations of pulmonary tuberculosis can pose a variety of diagnostic and management challenges.
The radiologic presentation of primary infection tends to differ from that of post primary pulmonary tuberculosis,
but there is significant overlap in the appearances.
Correct diagnosis and therapy is important for a good evolution.