Radiological features of pneumonia

Dr. Prithwiraj MaitiMBBS

House Physician, Department of Internal MedicineR.G.Kar Medical College

Admin and Founder, Pgblaster IndiaAuthor of: “A Practical Handbook of Pathology Specimens and Slides” and “An Ultimate Guide to Community Medicine”; published by Jaypee Brothers, India

Topics to be discussed: Radiological anatomy of lung Common radiological features of pneumonia1. Staphylococcus aureus2. Klebsiella pneumoniae3. Mycoplasma pneumoniae4. Pneumocystis carinii5. Mycobacterium tuberculosis6. Mycobacterium avium complex7. Hydatid disease of lung8. Allergic bronchopulmonary aspergillosis9. Candida albicans10. Bronchiectasis

Radiological anatomy of right lung 2 fissures, 3 lobes

Radiological anatomy of left lung1 fissure, 2 lobes

Common radiological features of pneumonia

1. Abnormal lung opacity2. Increase in the size and number of lung markings3. Silhouette signs: Loss of clarity of the diaphragm and heart borders 4. Air bronchogram lines5. Spine sign: Loss of the normal darkening inferiorly of the thoracic

vertebral bodies on the lateral view (suggesting lower lobe infection)6. Opacification of the lung behind the heart shadow or below the

diaphragms.

Common radiological features of pneumonia

1. There is a dense opacity within the right upper lobe of the lung (arrowed)

2. There are also air-bronchogram lines

3. There is increase in the number of bronchovascular markings

4. There is some loss of definition of the upper right heart border (silhouette sign).

There is abnormal opacity behind the left heart shadow (arrowed). There are air bronchogram lines.

Spine sign: This image shows the vertebral bodies become lighter as we move down (arrowed). This is caused by consolidation within the lower lobe.

Staphylococcus aureus• Age group: Infants/ children• Characteristic pneumatoceles (thin

walled cavities resulting from localized pulmonary destruction)• Bronchopneumonia• Multifocal and bilateral• Air bronchogram unusual• Lobar involvement unusual• In acute phase, it may cause cavitating

pneumonia with pleural effusion• May cause hydrothorax/

hydropneumothorax.

Klebsiella pneumoniae• Age group: Elderly patient• Upper lobe consolidation• Bulging fissure sign/ Bow

fissure sign.

Mycoplasma pneumoniae• Age group: 20-40 years• Initial stage: Unilateral lower

lobe involvement beginning at hilum, fanning out to periphery• Late stage: Segmental,

peribronchial involvement -> Lobar involvement.

Pneumocystis carinii• Age group: Children as well as

adults• Bilateral, symmetrical, diffuse,

fine to medium reticular opacities• Sometimes solitary/ multiple

miliary nodules/ thick walled nodules/ thin walled pneumatoceles are seen.

Mycobacterium tuberculosis: Primary TB

• Ghon’s complex: Tuberculoma (caseating granuloma) near interlobar fissure + hilar lymph node enlargement• Ranke’s complex: When a Ghon's

complex undergoes fibrosis and calcification with calcified draining lymphatics, it is called a Ranke complex.• Pleural/ pericardial involvement• Miliary/ extrapulmonary TB.

Ranke’s complex Miliary TB

Mycobacterium tuberculosis: Secondary TB

• Acinar consolidation• Cavitation• Endobronchial spread• Miliary pattern.

Arrow: Cavity, M: Miliary pattern

Mycobacterium avium complex (MAC)

• Nodules• Infiltration (patchy consolidation)• Cavity• Ectasia.

[Mnemonic: NICE, 1 or more may be present]

Hydatid disease of lung• Lung is the most common site of

secondary involvement in children• Predominantly lower lobe

involvement• Calcification of cyst wall rare• Rib/ vertebral erosion may occur.

Signs in hydatid disease of lungSign Cause Radiological representation

Meniscus/ Double arch/ Crescent/

Moon sign

Due to thin crescent of air in the uppermost of the cyst

Onion peel/ Cumbo sign

Due to air fluid level inside endocyst

Serpent sign Collapsed membranes inside the cyst outlined by air

Water Lilly sign Completely collapsed cyst floating on the cyst fluid

Cavity All contents of cyst breaks out via communicating bronchus

Allergic bronchopulmonary aspergillosis

• Air crescent/ Monad’s sign: Characteristic of aspergilloma -> Fungal ball with air crescent surrounding it.

Allergic bronchopulmonary aspergillosis

• Halo sign: Due to bleed in invasive aspergillosis.

Candida albicans• Rarely occurs in severely

immuno-compromised patients with leukemia/ lymphoma/ HIV patients• Widespread bilateral interstitial

fluffy alveolar infiltrates; sometimes progressing to lobar consolidation.

BronchiectasisCXR: • Dilated bronchi• Tram track appearance

HRCT:• Honeycombing

Thank you….Resources used: Radiology textbooks and Internet images.