Lung Nodules
Frans Naudé
Definition of Pulmonary nodule
• Rounded opacity , moderately well defined
• < 3cm in diameter
Web p 97
General Approach to lung nodules
Position
• Is it a lung nodule?
– Skin tags, nipple shadows, bone lesions
• Distribution in the lung
Number of Nodules ( SPN, Multiple)
Compare with previous radiographs
Interpreting CXR p102
Web p185
P84, Computed Tomography of the Lung, Verschakelen
Lung nodules: Imaging Modalities
• CXR
• CT ( HRES)
• PET/CT : F18-FDG
Description of pulmonary nodule
• Pattern of distribution (Relationship to
fissures, pleura, secondary lobules)
• Edge characteristics (sharp, poorly
circumscribed, ground glass)
• Morphology ( branching/ tree in bud)
• Size:
– Pulmonary nodule <3cm
– Small nodule < 1cm
Web p97 High resolution CT of the lung
Large nodules 1-3cm
(Easily seen on CXR)
HRES CT
Anatomy of pulmonary lobule
Secondary pulmonary lobule
(1) interlobular septa
(2) centrilobular region
(3) lobular lung parenchyma
Blue = Pulmonary veins
Green = lymphatic's
Yellow= bronchiolar branches
Red = Arteries
White = Connective tissue
Computed Tomography of the lung p9
Secondary pulmonary lobule
Prof Naidich
HRES CT
• Interstitial nodules
vs
Air space nodules
WEB-Algorithmic approach to nodules
Interstitial
Air space
Well defined
Ill defined
Soft tissue attenuation
Homogenous soft tissue
Obscure edges of vessels they
touch
Hazy and less dense than
adjacent vessels
Peripheral in Pulm. Lobule
Central
P120 High resolution CT lung ,Web - approach
CT of the lung , p74
CT of the lung , p72
HRES CT
High resolution CT lung ,Web – Algorithm 4
Airspace nodules
• = centrilobular distribution
• = no pleural/septal nodules
• Ground-glass opacification/ less dense than
adjacent blood vessels
Centrilobular nodules : Tree in Bud
Tree – in - Bud
• PT with TB
• Indicative of endobronchial
spread
P83, Computed Tomography of the Lung,Verschakelen
Infective bronchiolitis
 Tree in Bud appearance
 Bronchial wall thickening
Computed Tomography of the Lung,Verschakelen
HRES CT
Tree in bud
absent
High resolution CT lung ,Web - approach
Centrilobular: Tree in bud absent
Poorly defined hazy ground glass nodules
• Respiratory bronchiolitis
• Langercell histiocytosis
• Lymphocytic interstitial pneumonitis
Interstitial nodules
• = pleural/ septal predominance
HRES CT
Perilymphatic
High resolution CT lung ,Web - approach
Perilymphatic disease
• Clustered nodules
• Adjacent to fissures
and pleural surfaces
and along central
vascular structures
• DDX: Sarcoid, silicosis,
CWP.
• Rare: Amyloid ,LIP
• Sarcoidosis
P83, Computed Tomography of the Lung,Verschakelen
Silicosis
Web p305
Web p 306
Coal workers pneumoconiosis
Web p 306
Diffuse pattern more in favour of CWP or silicosis than sarcoidosis
HRES CT
Random
High resolution CT lung ,Web - approach
Random nodules
• Sharply define,+- feeding
vessel
DDX
1. Metastases: lung, breast,
kidney, colon, melanoma,
thyroid , pancreas
2. Infection: Milliary TB, septic
emboli, fungal infection
3. Vasculitis
4. Langercell histiocytosis
Metastases
• Random
• Basilar
predominance
P82, Computed Tomography of the Lung,Verschakelen
CT of the lung, p 75
Perilymphatic vs. centrilobular
Sarcoidosis
- Fissural and subpleural nodules
TB
Centrilobular changes : nodules, tree-inbud, branching lines
(A) Perilymphatic nodules.
Nodules are immediately in contact with
interlobular septa and the visceral pleura
(B) Centrilobular nodules. Nodules are positioned
5 - 10 mm from costal and visceral pleural surfaces
and interlobular septa.
High resolution CT lung ,Web - approach
References
•
•
•
•
High resolution CT of the lung, Web, Naidich
CT of the lung, Verschakelen, De Wever
Prof Naidich RSSA lecture
High-Resolution CT of the Lung: Patterns of Disease and Differential
Diagnoses, Radiol Clin N Am 43 (2005) 513 – 542
• Imaging of Interstitial Lung Disease, Radiol Clin N Am 43 (2005) 589 – 599
SPN
Def: focal area of increased round /oval density
in the lung parenchyma measuring less than
3cm,
Cause : infection, malignancy , inflammation,
vascular, congenital
Risk : 30-40% malignant
Radiographics 2000:20: 43
Approach to SPN
• Morphology:
• - Size ( smaller more likely benign)
• - margins and contours
Margins
Risk for malignancy
Smooth
21%
Lobulated ( uneven growth
75%
Irregular ,spiculated,
distortion of blood vessels
Very high risk
Internal characteristics
• Homogeneous attenuation (55% benign, 20%malignant)
• Pseudocavitation and air bronchograms: lymphoma or
bronchioalveolar cancer
• Benign cavitation : smooth ,thin walls (<4mm)
• Malignant cavitation: thick irregular walls( >16mm)
• Intranodular fat = hamartoma
• Benign calcification :
– post infection: central, diffuse solid, laminated ,
– hamartoma : popcorn like
• Malignant calcification: diffuse,amorphous,punctate
• Metastatic osteosarcoma: high attenuation nodule
• 25-39% malignant nodules classified as benign
on radiological morphology assessment
• growth rate assessment: doubling rate (
increase in diameter of >26%) for malignant
nodules between 30-400 days
• Clinical data: age, risk factors, previous
malignancy
Distribution of lung nodules
• Cancer – basal predominance
• Breast CA, Colon, Renal often metastasize to
lung
Interpreting CXR p100
Size of lung nodules
• Mayo clinic CT screening trial
• ( in patients with no history of cancer)
•
•
•
•
•
<3mm = less than 0,2% malignant
<5mm = fewer than 1% malignant
4-7mm = 0,9% malignant
8-20mm = 18% malignant
>20mm = 50% malignant
Radiology Nov 2005 p 397
Follow-up
National Lung Screening Trial
• nodules smaller than 4mm
• return for screening after 12 months, without
interval scans or other work-up
Radiology Nov 2005 p 397
Radiology Nov 2005 p 398