1-Characterization of the primary lesion.
- Benign characters: small lesion<2 cm, rounded, smooth edge, with calcium and no change in size over 2 years.
-Malignant characters: more than 2.5 cm, spiculated edge and no calcium with clinical history of smoking.
- A pulmonary nodule with spiculated margin and containing calcium, is malignant until prove otherwise(spiculated is a more powerful sign for malignancy than calcium as a sign of benign lesion).
-A pulmonary nodule with smooth margin and does not contains calcium needs further evaluation(undetermined nodule).
-Bronchogenic carcinoma could arise on top of calcified lesion(rare).
-Presence of pulmonary mass is suggestive of bronchogenic carcinoma whatever the shape of this mass, is it with spiculated margin or smooth one, is it containing calcium or not, this mass should be considered a bronchogenic carcinoma until prove otherwise.
-Two types of bronchogenic carcinoma, central type mainly represented by a mass, and peripheral type mainly represented by a nodule.
-Look carefully to the edge of the lesion(smooth, lobulated or spiculated), the nature if it is cystic or solid, and to the presence of calcium(presence of calcium in a nodule(1%) means benign lesion while its presence in a mass(15%) does not exclude malignancy).
-Enlarged unilateral hilar shadow with epsilateral diaphragmatic paralysis(epsilateral elevation of diaphragmatic copula) should be considered bronchogenic carcinoma until prove otherwise.
-Cavitating bronchogenic carcinoma which could be differentiated from pulmonary abscess by looking to the wall, in the former the wall will be thickened with irregular internal wall.
-A bronchogenic mass with mixed density ( cystic component with solid part ) should be considered as a solid tumor favoring malignancy.
-You should look for rib destruction in any case with peripheral pulmonary bronchogenic carcinoma.
-Differential diagnosis of a pulmonary mass:
*Bronchogenic carcinoma which is the most common cause.
*Lymphoma.
*Rounded pneumonia.
*Carcinoid tumor.
*Bronchoblastoma.
2-Local relationship to the pleura, chest wall, mediastinum and airways.
- Landmarks of chest wall invasion(peripherally located lesion):
* Tumor extension beyond the chest wall which is better evaluated by MRI.
* Rib destruction which is better evaluated by CT.
The tumor seen adherent to the chest wall without extension beyond it and without rib destruction does not means chest wall invasion.
Recently, chest wall invasion does not means in-operable case.
-Central mass:
You should verify the followings
*Air way involvement( Distance between the lesion and carina).
If the tumor is away from carina by more than 2 cm with invasion of mediastinal fat, this means operation can be done.
If the lesion is near the carina by less than 2 cm or invading one of the main structures of the mediastinum such as heart or superior vena cava, this means no operation.
Bronchial obstruction by the primary tumor causes obstructive pneumonia and atelectasis.
Anatomy of bronchi is better assessed by CT.
Separation of tumor tissue from atelectasis is better by MRI.
If you do MRI T2 for this case, you can separate easly between the edge of the mass and atelectasis as the latter contains much more water than the former resulting in hyper intensity of the latter if compared with low intensity of the former.
*Mediastinal invasion.
Minimal invasion in which the tumor invades mediastinal fat only, this is suitable for surgical resection if the distance between lesion margin and carina is greater than 2 cm.
Gross invasion with involvement of vital structures prevent surgical interference such as the pulmonary artery, superior vena cava, esophagus or the heart and pericardium.
-Most common sites for metastases in case of bronchogenic carcinoma are brain and supra renal glands.
-If you have a case of brain metastases of unknown primary site, just make a chest film, usually you can find this primary (golden rule).
4-Lymph nodes invasion
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