Pulmonary neoplasms
EVALUATION OF THE SOLITARY PULMONARY NODULE
EVALUATION OF THE SOLITARY PULMONARY NODULE
DEFINITION
• This is defined as a solitary circumscribed pulmonary opacity with no associated pulmonary, pleural, or mediastinal abnormality 
it measures < 3cm in diameter
• Many are discovered incidentally (but up to 40% may be malignant)
DIFFERENTIATION BETWEEN BENIGN AND MALIGNANT MASSES
• The two primary criteria are the rate of growth (or stability over time) and the attenuation of the nodule 
the patient’s age is also a significant distinguishing feature (a carcinoma is only seen in < 1% of patients < 35 years old)
Rate of growth/stability over time: benign lesions invariably have a doubling time of < 1 month or > 18 months (bronchoalveolar carcinomas are an exception in that they may have very slow growth rates) 
bronchial carcinomas usually have a doubling time of between 1 and 18 months
Attenuation/enhancement: a dense central nidus or laminated calcification indicates a granulomatous process (e.g. tuberculosis, histoplasmosis) 
irregular ‘popcorn’ calcification suggests a hamartoma 
fat is virtually diagnostic of a hamartoma 
a lack of enhancement (<15HU) following IV contrast medium is indicative of benignity
– Granular calcification is seen on CT in up to 7% of carcinomas (and can represent either tumour calcification or a granuloma engulfed by tumour)
– A mixture of soft tissue and ground-glass attenuation nodules is more likely to be malignant than soft tissue nodules alone
Size: this is of little diagnostic value
Margins: a well-defined mass with a smooth pencil sharp margin is likely to be benign 
carcinomas typically have ill-defined margins which are irregular, spiculated, or lobulated and may exhibit umbilication or a notch – unfortunately all these features can be seen with benign disease
a positive result is 97% sensitive and 82% specific for malignancy
it can also occur if the nodule is due to a carcinoid tumour or a slow-growing broncho-alveolar carcinoma
Simulants of solitary pulmonary mass*
Extrathoracic artefactsCutaneous massesBony lesionsPleural tumours of plaquesEncysted pleural fluidPulmonary vessel
Causes of a solitary pulmonary mass*
Bronchial carcinomaBronchial carcinoidGranulomaHamartomaMetastasisChronic pneumonia or abscessHytadid cystPulmonary haematomaBronchoceleFungus ballMassive fibrosis in coal workersBronchogenic cystSequestrationAtriovenous malformationPulmonary infarctRound atelectasis
Radiological features of solitary pulmonary nodules and the likelihood of malignancy
| Feature/Characteristic | LR* |
| Spiculated margin | 5.54 |
| >3cm in size | 5.23 |
| >70 years of age | 4.16 |
| Malignant growth rateβ | 3.40 |
| Smoker | 2.27 |
| Upper lobe location | 1.22 |
| <1cm in size | 0.52 |
| Smooth margins | 0.30 |
| 30–39 years of age | 0.24 |
| Never smoked | 0.19 |
| 20–29 years of age | 0.05 |
| Benign calcificationα | 0.01 |
| Benign growth rateµ | 0.01 |
NB: a likelihood ratio of 1.0 indicates a 50% chance of malignancy 
a likelihood ratio < 1.0 typically indicates a benign lesion 
a likelihood ratio > 1.0 typically indicates a malignant lesion
*Likelihood ratio (LR)
αBenign calcification: diffuse, central, popcorn or concentric
µBenign growth rate: a volume doubling time < 1 month or > 2 years (approximately)
βMalignant growth rate: a volume doubling time > 1 month or < 2 years (approximately)
Adapted from Erasmus et al. Radiographics 2000; 20: 59–66.
LUNG CANCER: RADIOLOGICAL FEATURES
LUNG CANCER: RADIOLOGICAL FEATURES
DEFINITION
• SCLC: small (oat) cell carcinoma
This originates from submucosal neuroendocrine cells 
it rapidly spreads haematogenously and to the lymph nodes 
it behaves as a systemic disease and is usually disseminated at presentation
• NSCLC: non-small cell lung cancer
Squamous cell carcinomas: arises from the proximal airway epithelium
Large cell carcinomas: atypical cells that appear ‘large’ under the microscope
Adenocarcinomas: arising from the bronchial glands
Bronchoalveolar carcinoma: an adenocarcinoma subtype arising from the alveoli and adjacent small airways (probably from type II pneumocytes) 
it presents as peripheral pulmonary opacities
• Risks: tobacco smoke (with a 20–30 fold increased risk) – this has the greatest association with squamous cell carcinomas and the weakest association with bronchoalveolar carcinomas 
asbestos exposure, interstitial pulmonary fibrosis and radiotherapy are additional risks
CLINICAL PRESENTATION
• Asymptomatic (25%): asymptomatic peripheral tumours are more likely to be incidental findings and surgically resectable
• Symptomatic: recurrent pneumonia 
cough 
wheeze 
haemoptysis
• Paraneoplastic syndromes: inappropriate ADH secretion 
Cushing’s syndrome (ACTH) 
carcinoid syndrome 
hypercalcaemia (PTH)
• Poor prognostic features: hoarseness 
chest pain 
brachial plexus neuropathy or Horner’s syndrome (due to a Pancoast’s tumour) 
SVC obstruction 
dysphagia
RADIOLOGICAL FEATURES
Peripheral tumours
• The majority are spherical or oval in shape 
lobulated masses can occur due to uneven growth rates 
there may be a ‘corona radiata’ due to numerous fine strands radiating into the lung 
a bronchocele or mucoid impaction can be seen distal to an obstructing carcinoma 
collapse and consolidation is less commonly seen than with central tumours
Cavitation with irregular thick walls ± fluid levels (particularly squamous tumours)
Calcification is rare (6–10%) and may represent engulfed granulomatous disease
Air bronchograms are rare but can be seen with bronchoalveolar carcinoma and adenocarcinoma
• Ground-glass attenuation is associated with a higher risk of malignancy (and commonly seen with bronchoalveolar carcinoma)
any peripheral collapsed lung will enhance more than a central tumour 
collateral air drift may prevent some post-obstructive changes
extensive hilar and mediastinal lymphadenopathy is typical of small cell tumoursChest wall invasion (T3)
• This does not preclude surgical resection (although it adversely affects the prognosis)
• CT: assessment is unreliable (with local chest wall pain remaining the most specific indicator) 
contact with or a thickened pleura does not necessarily indicate invasion 
a clear extrapleural fat plane is helpful but not definitive 
reliable signs include clear-cut bone destruction or a large soft tissue mass
• MRI: this is better than CT in selected cases 
it is the optimal modality for demonstrating the extent of a superior sulcus tumour
• Transthoracic ultrasound: this is an accurate technique
• 99mTc radionuclide skeletal scintigraphy: this is sensitive (and may detect bone invasion before plain radiography)
Mediastinal invasion (T4)
• CT/MRI indicators: visible tumour deep within the mediastinal fat (mediastinal contact alone is not enough to diagnose invasion) 
encasement of the mediastinal vessels, oesophagus, or proximal mainstem bronchi 
SVC obstruction 
an elevated hemidiaphragm (indicating phrenic nerve involvement)
• Criteria for resectability: < 3cm of contact with the mediastinum 
< 90° of circumferential contact with the aorta 
a visible mediastinal fat plane between the mass and any vital mediastinal structure
• Irresectability: tumours obliterating fat planes or showing greater contact than that described above
haematogenous osteolytic bone metastases 
hypertrophic osteoarthopathy
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