Chest Radiology

Chest Radiology > Pathology > Lung Cancer

Lung Cancer

The cell type of primary malignancies of the lung can often be distinguished by their pattern of growth, appearance and location. Across the world, lung cancer causes to more cancer deaths than any other tumor.

The most common staging system used for non-small cell lung cancer is the TNM staging as follows:

The best chance for cure is resection of the tumor. However, it has been found that not all patients with lung cancer will benefit from surgery. These tumors are thereby unresectable as below. Other patients may be “unresectable” due to comorbidities such as emphysema or cardiac disease.

Lung cancers are unresectable once they have progressed to a TNM staging of any of the below.

T4 – Invasion of the mediastinum or involvement of the heart, great vessels, trachea, esophagus, vertebral body, or carina; or neoplasia associated with a malignant pleural or pericardial effusion, or satellite nodules in the same lobe
N3 – Metastasis to contralateral mediastinal and hilar nodes, ipsilateral or contralateral scalene or supraclavicular nodes
M1 – distant metastasis present

T4 or N3 would stage the tumor IIIB, M1 would stage it Stage IV.

The above CT image shows the spiculated appearance of a lung cancer.

The six cell types of primary lung carcinomas with their typical appearances are as follows:

Adenocarcinoma – (35-50%) Peripheral, sometimes associated with scars, high incidence of early metastasis
Squamous Cell Carcinoma – (30%) Central, with hilar involvement, cavitation is common, slow growing
Small Cell - (15-20%) Central, cavitation is rare, hilar and mediastinal masses often the dominant feature, rapid growth and early metastases
Large cell – (10-15%) Peripheral, large, cavitation present
Bronchaveolar – (3%) Peripheral, rounded appearance, pneumonia-like infiltrate (air bronchograms), occasionally multifocal
Carcinoid – (less than 1%) Typically a well defined endobronchial lesion; nodal, liver and brain metastases may enhance densely (i.e. They may be hypervascular)

The above image shows a right lower lobe squamous cell cancer. Notice the cavitation, which is found more characteristically in squamous cell than in other bronchogenic carcinomas.