Differential diagnosis for round pneumonia?
• pulmonary masses o bronchogenic cyst o neuroblastoma o type III CCAM o pulmonary metastases o pleural fibroma o fungal infection o pulmonary sequestration
What is tree in bud appearance on CT?
- describes the CT appearance of multiple areas of centrilobular nodules with a linear branching pattern
- can be due to disease in distal airways (at the level of bronchiole, small airway disease) or distal vasculature
- usually due to endobronchial spread of infection
- Invasive pulmonary aspergillosis
- TB - endobronchial spreading
- NTM
- ABPA
Causes of centrilobular nodules?
- things that enter lung through airway can give centrilobular nodules
- Hpersensitivity pneumonitis
- Infection - TB, mycoplasma
Is you see an area of opacification on CT, what are the 2 terminology descriptions?
- Consolidation: ● Increase in lung opacity obscuring vessels, may see air bronchograms since air can still be present in airways
- Ground glass opacification: ● Hazy increase in lung opacity without obscuration of underlying vessels
What is crazy paving and differential diagnosis for crazy paving?
Ground glass superimposed on septal thickening
Differential:
- PAP
- Infection like PJP (which can also cause PAP)
- ARDS
- diffuse alveolar hemorrhage
- organizing pneumonia
- lipoid pneumonia
What is the difference between high attenuation versus low attenuation lesion on CT scan?
- High attenuation - something that is occupying and displacing air and appears white–>opacity
- Low attenuation - increased air content, appears black –>lucency
What are signs of bronchiectasis on CT?
- bronchus visualised within 1 cm of pleural surface
* especially true of lung adjacent to costal pleura * most helpful sign for early cylindrical change * lack of tapering * increased bronchoarterial ratio 9
* diameter of a bronchus should measure approximately 0.65-1.0 times that of the adjacent pulmonary artery branch * between 1 and 1.5 may be seen in normal individuals, especially those living at high altitude * greater than 1.5 indicates bronchiectasis
A number of ancillary findings are also recognised:
*
bronchial wall thickening: normally wall of bronchus should be less than half the width of the accompanying pulmonary artery branch
*
mucoid impaction
*
air-trapping and mosaic perfusion
Signs described on CT include: * tram-track sign * signet ring sign
Causes of diffuse cystic lung disease?
- lymphangioleiomyomatosis (these women often get pneumothorax)
- Birt-Hogg-Dubé syndrome
- pulmonary Langerhans cell histiocytosis
- desquamative interstitial pneumonia
- lymphocytic interstitial pneumonitis (LIP, which is associated with HIV)
PJP
(I think BPD could also be on this list, Filamin A mutation)
Differential diagnosis for honeycombing?
● Fibrosis ○ IPF/UIP ○ RA, scleroderma ○ Drug reaction ○ End-stage HP ● End-stage sarcoidosis
Differential diagnosis for mediastinal lymphadenopathy?
● Lymphoma
● Infection: TB, histoplasmosis
● Sarcoidosis (symmetric)
● Silicosis
Other: pneumonia, scleroderma
Differential diagnosis for anterior, middle and posterior mediastinal mass?
- Anterior: posterior sternum to pericardium. Thymoma, termatoma, lymphoma, goitre
- Middle mediastinum: anterior pericardium to ventral surface of thoracic spine. Lymphadenopathy, bronchogenic cyst, esophageal tumor, vascular mass/enlargement
- Posterior (spine): meningocele, neuroblastoma, gastroenteric duplication cyst (can present in infants and there can be associated vertebral anomalies)
- foregut duplication cyst is a more generic name for cysts, including bronchogenic cyst and enteric cyst
Differential diagnosis for hyperlucency and mediastinal shift on an infant’s CXR?
- pneumothorax
- congenital lobar emphysema
- CPAM
- absence of contralateral lung
- CDH
Other:
- PIE (there would be a pattern of hyerlucency in the interstitium, but I’m not sure if there would be mediastinal shift)
- foreign body
Radiopedia:
bronchial atresia: the parenchyma distal to the atretic segment can have air trapping
congenital pulmonary airway malformation (CPAM)
pulmonary arterial hypoplasia
pulmonary hypoplasia
Swyer-James syndrome - unilateral BO, the affected lung is hyperinflated and hyperlucent
filamin A mutation
Other:
Air: pneumothoax, pneumonectomy
Obstruction: * foreign body * airway obstruction - endobronchial TB, carcinoid, mucous plug * Swyer James
Unilateral large bullae
Differential diagnosis for unilateral diaphragm elevation on imaging?
Above the diaphragm
- Atelectasis
- Pulmonary hypoplasia
- Prior lobectomy and pneumonectomy
- diaphragmatic hernia
- Sub-pulmonic effusion (between lung and diaphragm)
Within the diaphragm
- Diaphragm eventration
- Diaphragm paralysis - tumor, viral infection like HSV, surgical injury
Below the diaphragm
- Abdominal mass
- Sub-phrenic abscess
- Distended colon or stomach
What is a ground glass opacity? Differential diagnosis?
increased attenuation, but you can still see bronchial and vascular markings
- it could be due to alveolar process (due to partial filling or collapse, in contrast to consolidation) or could be an interstitial process
- Infection:
- PJP
- Viral - CMV, RSV, influenza, paraflu
(you generally aren’t thinking of a typical bacterial pneumonia with ground glass, these would usually cause consolidation) - Drug toxicity
- Alveolar - ARDS, edema, TRALI, DAH
- interstitial diseases–COP, eosinophilic pneumonia, sarcoid
Differential diagnosis for pulmonary consolidation?
- fill up alveoli
- common to get associated air bronchograms
- typical infection
- edema
- PAP
- ARDS
- lipoid pneumonia
- aspiration pneumonia
- DAH
- other: COP, eosinophilic pneumonia
Causes of mosaic attenuation?
- patchwork of different attenuations due to:
- ground glass
- airway disease
- vascular disease
- air trapping
- bronchiolitis obliterans
- pulmonary hypertension
- thromboembolic disease
Nodules in an immunocompromised patient, differential diagnosis?
Infectious - fungal, nocardia, viral, bacterial
PTLD
malignancy
septic emboli
What is “tree in bud” and what is differential diagnosis?
- branching pattern of centrilobular nodules
- there is distal vasculature and airway at the centre of the nodule
- it was initially described as a feature of endobronchial spread of TB, but other associations:
- ABPA
- aspergillus
- NTM
- pretty long differential, including vascular abnormalities
CT findings of pulmonary embolism?
- with CTPA: filling defect
- chronic PE:
- calcification of vessel
- mosiac perfusion
- if associated PH:
- enlargement of pulmonary artery
Differential diagnosis for multiple cavitary lung nodules?
- Vascular: septic emboli
- Infectious - TB
- Inflammatory: GPA, RA, IBD (necrobiotic nodules)
- Malignancy - metastatic disease
Differential diagnosis for cavitary lung lesion?
- Infectious:
- common bacteria (for example, Streptococcus p., Staph.aureus, Klebsiella p., H. influenzae); typical and atypical mycobacterium; fungi (for example, aspergillosis, pneumocystis j.); and parasites
- septic emboli
Opacity on CXR that looks more interstitial than alveolar. how to describe this?
“infiltrate” = linear opacity (technically opacity is preferred infiltrate, but i need some language to describe interstitial findings)
–>diffuse reticular/nodular/reticulonodular
What is Swyer James?
hyperlucent, unilateral, not hyper inflated
Swyer James is unilateral BO—don’t get hyperinflation, just get more black due to air-trapping, basically the lung which had the infection become hypoplastic
What is the complication of Swyer James: pulmonary hypertension due to hypoplastic vascular development, it’s the same idea as pulmonary hypoplasia
Most of the cardiac output is probably going to left and so the left sided vessels are juicier, so this will likely cause pulmonary hypertension
Symptoms: less exercise tolerance, hypoxemia, dyspnea on exertion
Need echos for PH
Generally conservative management and watch for PH
What is the air crescent sign and what causes it?
- round opacified nodule with crescent of air
- causes:
- invasive aspergillosis
- GPA
- TB
- hydatid cyst
- lung cancer
- PJP
