What are granulomas on a chest x-ray?

What Are Granulomas on Chest X-Ray?

Granulomas on chest x-ray are small nodular densities that represent organized collections of inflammatory cells, typically appearing as calcified nodules, fibrotic scars, or areas of apical pleural thickening, most commonly indicating healed tuberculosis or other prior granulomatous infections. 1

Radiographic Appearance

Granulomas manifest on chest radiographs with several characteristic patterns:

• Calcified nodular lesions (calcified granulomas) appear as discrete, well-defined densities and indicate lower risk for disease progression 1
• Fibrotic scars and nodules may contain slowly multiplying organisms and pose higher risk for reactivation 1
• Apical pleural thickening is considered evidence of prior tuberculosis, particularly when accompanied by apical fibronodular infiltrations with volume loss 2
• Upper lobe infiltrates with patchy or nodular patterns are characteristic, especially in the apical or subapical posterior upper lobes 1

Common Causes

Infectious Granulomas

The most frequent causes include:

• Tuberculosis: Produces nodules, fibrotic scars, calcified granulomas, and apical pleural thickening as healed disease 1
• Nontuberculous mycobacteria (particularly MAC): Can cause discrete centrilobular and bronchiocentric granulomas 1
• Fungal infections: Various fungi can trigger granulomatous reactions 3

Non-Infectious Granulomas

• Sarcoidosis: Shows small, well-defined nodules in relation to lymphatic routes with middle or upper lobe predominance 4
• Hypersensitivity pneumonitis: Presents with ill-defined centrilobular nodules and ground-glass opacity 4
• Aspiration pneumonia and talc granulomatosis: Less common causes 3

Distinguishing Active from Healed Disease

A chest radiograph alone cannot distinguish between current and healed tuberculosis 1. Critical distinctions include:

• Healed disease: Nodules, fibrotic scars, calcified granulomas, and apical pleural thickening without progression 1
• Active disease: Upper-lobe infiltration, cavitation, pleural effusion, and progressive changes on serial imaging 1
• Comparison with prior radiographs is essential to confirm stability over time 2

Clinical Implications

Risk Assessment

• Patients with radiographic evidence of prior TB have approximately 2.5 times higher risk of reactivation compared to those with latent TB infection without radiographic abnormalities 2
• Calcified granulomas indicate lower progression risk, while nodules and fibrotic scars pose substantial risk 1

When Further Evaluation Is Needed

Sputum examination is indicated for:

• Any respiratory symptoms suggestive of active disease 1
• Chest radiographic findings consistent with TB disease 1
• HIV-infected persons with any pulmonary symptoms regardless of radiograph findings 1
• Uncertain treatment history requiring exclusion of active disease 2

Common Pitfalls to Avoid

• Do not confuse apicopleural thickening with active tuberculosis—they have distinct radiographic appearances 2
• Avoid unnecessary anti-TB treatment for radiographic findings representing healed disease 2
• Do not mistake other causes of apical pleural thickening (such as prior pleuritis or trauma) for TB sequelae 2
• Never rely on chest radiograph alone to exclude active disease when clinical suspicion exists; sputum examination or advanced imaging may be necessary 1

Follow-Up Recommendations

For patients with granulomas from prior TB:

• Clinical monitoring every 3 months during the first year after completing treatment 2
• Repeat chest imaging only if new symptoms develop 2
• Patient education about symptoms of TB reactivation requiring immediate evaluation 2
• Consider treatment for latent TB infection with 9 months of isoniazid if treatment history is uncertain 2