Tuberculosis on chest X-ray

Written by the X-Ray Atlas editorial team from the sources listed below · Medical review pending · Updated 24 October 2026 · Level: Intermediate

Tuberculosis (TB), caused by Mycobacterium tuberculosis, remains one of the world's leading infectious causes of death, and the UK still sees several thousand cases a year, concentrated in large cities and in people born in high-incidence countries. The chest X-ray is central to its detection: in people with symptoms, in contact tracing, and in screening before treatments that suppress immunity. TB is a great mimic, and its appearance depends on whether the infection is primary or post-primary (reactivation), on the patient's immune status, and on whether it is active or healed. This page covers the main patterns, the complications, the mimics and the limits of the film. Diagnosis rests on microbiology, not imaging.

1. How to look

Use the full systematic approach, then pay special attention to:

• the apices and upper zones, partly hidden by the clavicles and first ribs (an apical lordotic view was used historically to clear them; CT is now preferred when in doubt);
• the hila and right paratracheal region, for lymphadenopathy;
• the pleura, for effusion, thickening and calcification;
• any cavity: its wall thickness, contents and surrounding consolidation;
• comparison films: TB activity is often judged by change over time.

2. Primary TB

Primary infection is the first encounter with the organism, and is the typical pattern in children. Many primary infections are controlled by the immune system and are never seen.

• The Ghon focus is a small peripheral area of consolidation, often in the middle or lower zones (in contrast to reactivation TB).
• The Ghon (primary) complex is the Ghon focus plus ipsilateral hilar or paratracheal lymphadenopathy. Lymphadenopathy may be the only finding, particularly in children, and is often unilateral.
• When both components calcify, the result is called the Ranke complex, a sign of healed primary infection.
• A pleural effusion may occur, typically in adolescents and young adults.
• Enlarged nodes can compress a bronchus, causing collapse or hyperinflation, especially in young children.

3. Post-primary (reactivation) TB

Post-primary TB usually results from reactivation of latent infection years later, and is the typical adult pattern. It favours the best-oxygenated parts of the lung:

• the apical and posterior segments of the upper lobes, and the superior (apical) segment of the lower lobes.

The features are:

• patchy, ill-defined consolidation in those segments;
• cavitation, typically with moderately thick walls. Cavitation implies a high organism load and greater infectiousness;
• fibrosis with upper-lobe volume loss and elevated hila;
• calcification, which suggests older disease but does not on its own prove inactivity;
• spread through the airways, which on CT gives a "tree-in-bud" pattern and on the chest X-ray shows as patchy nodular opacities elsewhere in the lungs.

Lymphadenopathy is less common in post-primary disease than in primary TB in immunocompetent adults. A tuberculoma, a well-defined rounded nodule that may contain calcification, is another presentation and can mimic a tumour. See lung nodules and masses.

4. Miliary TB

Miliary TB is haematogenous spread, seen in primary or post-primary disease, especially in the very young, the old and the immunosuppressed.

• Innumerable tiny nodules, about 1–3 mm, of uniform size, evenly distributed through both lungs, like millet seeds.
• The film may be normal early in the illness; the nodules can be hard to see until they are well established.
• The differential includes miliary metastases (for example thyroid and renal carcinoma, and melanoma), sarcoidosis, histoplasmosis and pneumoconiosis.

Miliary TB is a medical emergency: the patient is often systemically unwell, and the disease may involve the meninges and other organs.

5. Pleural TB

• A unilateral effusion, often moderate in size, may be the only sign.
• Empyema can develop, and long-standing disease leaves pleural thickening and calcification, sometimes encasing the lung (a "fibrothorax").
• Pleural fluid analysis and pleural biopsy are used for diagnosis; the film only prompts it.

6. Healed and treated TB

• Calcified granulomas and calcified hilar or mediastinal nodes.
• Apical scarring with volume loss, elevated hila, tracheal deviation towards the scarred side, and bronchiectasis in the fibrotic lobe.
• Pleural calcification, often unilateral.
• Historical surgical treatments seen in older patients: thoracoplasty (removal of upper ribs to collapse the lung) and plombage (inert material, sometimes "Lucite balls", inserted to collapse the apex).

7. TB in HIV and immunosuppression

With advanced HIV or other severe immunosuppression, TB often looks atypical, more like primary TB:

• lower-zone or diffuse disease rather than apical;
• lymphadenopathy is common, and cavitation is less common;
• miliary and extrapulmonary disease are more frequent;
• the chest X-ray may be normal despite active disease.

Other infections enter the differential, for example Pneumocystis jirovecii pneumonia (PCP), which typically causes bilateral perihilar ground-glass or reticular opacity, sometimes with cysts (pneumatoceles) and pneumothorax.

8. Complications and look-alikes

• Aspergilloma (mycetoma): a fungal ball growing in an old cavity. It forms a rounded opacity in the cavity with a crescent of air around it (the air crescent or Monod sign), and it moves when the patient changes position. It can cause severe haemoptysis.
• Bronchiectasis in the scarred upper lobes.
• Pneumothorax from rupture of a cavity.
• Lung abscess is a common mimic: a thick-walled cavity with an air–fluid level, often in dependent segments after aspiration.
• Cavitating lung cancer (often squamous cell carcinoma) and granulomatosis with polyangiitis can mimic a TB cavity.
• Silicosis causes upper-zone nodules and fibrosis, and increases the risk of TB.
• Sarcoidosis causes nodes and upper-zone fibrosis, and is an important look-alike. See interstitial lung disease.

9. Next steps

• Microbiology confirms TB. NICE NG33 recommends sputum (or other samples) for smear microscopy, culture and rapid molecular tests. The film cannot distinguish TB from its mimics with certainty.
• A normal chest X-ray does not exclude TB, particularly early disease, extrapulmonary TB and TB in immunosuppressed people. If suspicion is high, investigate further (samples, CT, specialist referral).
• Suspected infectious (especially cavitating) pulmonary TB needs infection control measures in hospital, according to local policy.
• Chest X-rays are also used to look for active disease before treating latent TB and in contact tracing, according to national guidance.

Red flags: act now

What to focus on, by role

Role	Priorities
Medical student	Primary versus post-primary distribution, the Ghon and Ranke complexes, cavitation, the miliary pattern and the main mimics.
Nurse	Isolation and infection control for suspected pulmonary TB, sputum collection and recognising the unwell patient.
Junior doctor	Send the right samples, involve respiratory or infectious diseases early, and do not rely on a normal film to exclude TB in a high-risk patient.
Radiographer	Infection control in the department, and good apical coverage.
Advanced / FRCR	Activity assessment on serial films, TB in HIV, aspergilloma and differentials of upper-zone fibrosis and cavitation.

Practise on real chest X-rays →

References

1. NICE. Tuberculosis (NG33). nice.org.uk
2. Radiopaedia. Pulmonary tuberculosis. radiopaedia.org
3. Hansell DM, et al. Fleischner Society: glossary of terms for thoracic imaging. Radiology 2008. pubs.rsna.org
4. Royal College of Radiologists. iRefer. irefer.org.uk

For education only. Not a substitute for a formal report, senior review or your local policy. Never use this page to make decisions about a real patient.