See: [[Pneumonia scores]], [[paediatric pneumonia]] See: [Schwartz radiology - pneumonia](x-devonthink-item://2A71AF1A-4715-4D5F-9841-03401D8E6C4E?page=30) #radiology | pattern | organisms | pathology | radiographic findings | | ------------------------------- | --------------------------------------------------- | ----------------------------------------------------------------------------------------------------------------------- | ----------------------------------------------------------------------------------------------------------------- | | Lobar pneumonia <br>(segmental) | - strep pneumoniae<br>- klebsiella | alveoli filled with purulent exudate, alveolar walls not thickened | focal airspace filling<br>*air bronchograms* | | bronchopneumonia<br>(lobular) | - S aureus<br>- aspiration<br>- pseudomonas<br>- TB | infection in bronchus spreads distally to segmental airspaces; also may spread proximally to affect other lung segments | patchy airspace filling<br>involves one segment or multifocal; abscess or cavity formation<br>no air bronchograms | | interstitial pneumonia | - viral<br>- mycoplasma<br>- pneumocystis | alveolar walls thickened by inflammatory cells, spreads to adjacent airspaces | *reticular* or reticulonodular pattern. diffuse, patchy, or focal airspace filling | # CXR findings in pneumonia #radiology ## Lobar pneumonia ![[Pasted image 20241004131857.png]] - airspace disease in right upper lobe occupying entire lobe. white arrow shows horizontal fissure as inferior margin of pneumonia. black arrow shows fluid density of pneumonia where it comes in contact with ascending aorta ## Bronchopneumonia > can be a pattern of tuberculosis reactivation ![[Pasted image 20241004132951.png]] - multiple irregularly marginated patches of airspace disease in both lungs (white arrows) - disease spread via tracheobronchial tree to many foci in the lung, often involves several segments - **no air bronchograms** because inflammatory exudate fills the bronchi and airspaces around them ![[Pasted image 20241004133315.png|another example of bronchopneumonia]] ## Interstitial pneumonia - involves airway walls and alveolar septa → produces fine, *reticular* pattern in the lungs - often spread to adjacent alveoli and produce patchy or confluent airspace disease, making it difficult to appreciate original interstitial nature of pneumonia - mycoplasma pneumonia and PJP common interstitial pneumonia ![[Pasted image 20241004133637.png]] **PJP pneumonia** - bilat, centrally-located interstitial lung disease that is reticular - no pleural effusions (makes interstitial oedema less likely) - no hilar adenopathy (as you might see in sarcoidosis) ![[Pasted image 20241004133752.png]] Varicella pneumonia ## Round pneumonia in children, some pneumonias assume a spherical shape on CXR ![[Pasted image 20241004133959.png]] soft tissue density in right midlung (white arrows). this is a 10 month old child with cough and fever. usually due to haemophilus, streptococcus, or pneumococcal ## Cavitary pneumonia common in reactivation tuberculosis but rare in primary tuberculosis also caused by: - staph pneumonia → produce thin wall pneumatoceles - strep pneumonia - klebsiella pneumonia - coccidiodomycosis ## aspiration pneumonitis / pneumonia usually in the most dependent portions of the lung # Silhouette signs to diagnosis pneumonia Silhouette signs occur when the airspace of the lung are filled with fluid resulting in abnormal air/fluid interface or obliteration of a normal air/fluid interface (loss of a silhouette). There are four silhouette signs that may show a pneumonia: 1. Obliteration of a normal lung/soft tissue interface 2. loss of normal lung markings 3. air bronchogram or air alveologram 4. accentuated interlobular fissure | structure no longer visible | location of pneumonia | | --------------------------- | -------------------------- | | ascending aorta | right upper lobe | | right eart border | right middle lobe | | right hemidiaphragm | right lower lobe | | descending aorta | left upper or lower lobe | | left heart border | lingula of left upper lobe | | left hemidiaphragm | left lower lobe | ![[Pasted image 20241004134852.png]] silhouette sign showing right heart border pneumonia (arrow to bullet to show how appearance is misleading on PA) ![[Pasted image 20241004134936.png]] silhouette sign left heart border # false positives on CXR - poor inspiration → crowding of lung markings at the lung bases - lower lobe pulm arteries → on PA and lateral radiographs - overlying soft tissue → breast, pec muscle, chest wall lesions, nipples, clothes - skeletal lesions → vertebral body osteophyte, healed rib fracture, calcified costal cartilage - [[Radiology signs with names#Mach effect|Mach effect]] - pseudomediastinum