If a tumor is on the periphery of the lung, it usually cannot be seen with bronchoscopy. Instead, a biopsy may often be taken through a needle inserted through the chest wall and into the tumor. Typically, a chest X-ray or CT scanning is used to guide the needle. This procedure is usually safe and effective in obtaining sufficient tissue for diagnosis.
After the chest surface is cleaned and prepared, the skin and the chest wall are numbed. The most serious risk is that the needle puncture may cause an air leak from the lung (pneumothorax). This air leak occurs in as many as 20% of cases. Many are so small, though, that they don't need treatment. Only about 3% will require a chest tube. Although the leak can be dangerous, it is almost always recognized and treated without serious consequences.
Thoracentesis Lung cancers, both primary and metastatic, can cause fluid to collect in the sac surrounding the lung. This is called pleural effusion. The fluid usually contains cancer cells. Sampling this fluid can confirm the presence of cancer in the lungs. The fluid sample is removed by a needle in a procedure similar to needle biopsy. Thoracentesis can be important for both staging and diagnosis of the condition.