TRANSTHORACIC NEEDLE BIOPSY

Indications

Transthoracic needle biopsies (Box 19-1) are performed most commonly for the diagnosis of an indeterminate solitary pulmonary nodule. Not all solitary pulmonary nodules that are suspect for bronchogenic carcinoma require biopsy. If the pretest probability is very high for lung cancer or a biopsy is unlikely to have any impact on management, TNB should not be performed. For example, if a patient presents with a long history of smoking and a new, irregular, spiculated nodule in the lung, the likelihood is extremely high that this represents a lung cancer, and it is reasonable to proceed directly to staging and resection. Other indications for TNB include undiagnosed mediastinal masses, a hilar mass when the bronchoscopy result is negative, single or multiple pulmonary nodules in a patient with a known extrathoracic malignancy or a suspicion of metastatic disease, and suspected infectious lesions manifesting as solitary nodules, masses, or very focal areas of consolidation, particularly in the immunocompromised host.

Box 19-1 Indications for Transthoracic Needle Biopsy

Indeterminate solitary pulmonary nodule

Undiagnosed mediastinal mass

Hilar mass when bronchoscopy is negative

Single or multiple nodules when metastases are suspect

Probable infectious lesions presenting as nodules or masses

There are several diagnostic alternatives to TNB. The most important is bronchoscopy. However, bronchoscopy is preferred for central lesions, particularly if a prebronchoscopy CT scan shows evidence of endobronchial involvement. Transthoracic biopsy may be used to diagnose hilar masses when the result of bronchoscopy is negative and extraluminal compression of the airway is identified. Transbronchial needle aspiration (i.e., Wang needle) is primarily used to establish metastatic malignancy in mediastinal nodes for the purposes of staging lung cancer. A needle is inserted using the bronchoscope through the tracheal wall or carina to facilitate the biopsy of the nodes. In the absence of a visible endobronchial lesion, the diagnostic yield for bronchoscopy in peripheral nodules is low (in the range of 58% to 80%) and is lowest for nodules less than 2 cm in diameter. Video-assisted thoracoscopy enables the diagnosis of peripheral subpleural pulmonary lesions. However, this is an operative procedure that requires an inpatient stay and general anesthesia, and it is more expensive than bronchoscopy or transthoracic needle aspiration biopsy.

Contraindications

Most contraindications to TNB are relative rather than absolute (Box 19-2). The most important are bleeding diatheses. A prebiopsy prothrombin time (PT), partial thromboplastin time (PTT), and platelet count are recommended. A careful history of coagulation abnormalities or the ingestion of drugs such as aspirin, which may lead to abnormal platelet function, should be obtained. Patients with low platelet counts who require an emergent biopsy, such as an immunocompromised patient with pulmonary infection, can receive platelet transfusions. Biopsy of lesions that have a marked vascular supply should be avoided.

Another relative contraindication is pulmonary hypertension. Needle biopsy can be safely attempted in patients with mild pulmonary hypertension if the nodule is peripheral. In the case of deep nodules or hilar masses, it is not recommended. Other relative contraindications include mechanical ventilation, bullae, or severe emphysema in the path of the lesion to be biopsied, severe chronic obstructive pulmonary disease (COPD, defined by a forced expiratory volume in 1 second [FEV₁] of less than 1 L), and intractable cough.

Patients should be cooperative and be able to maintain a certain position. Biopsies are performed with patients in the supine or prone position. The decubitus position is less preferable because it is difficult for the patients to maintain the position.

Local Anesthesia and Sedation

Lung biopsies can be performed under local anesthesia and breath-hold technique or under local anesthesia and intravenous conscious sedation with quiet breathing. Uncooperative patients need conscious sedation.

Technique

Prebiopsy Imaging

Computed tomography (CT) is highly recommended before TNB. CT is useful in providing a specific benign diagnosis in certain instances, such as a calcified granuloma or hamartoma, and it can provide information concerning the optimal approach to the lesion (Figs. 19-1 and 19.2). Areas of necrosis within large masses can be identified. Such areas should be avoided because they often produce nondiagnostic samples. ¹⁸F-fluorodeoxyglucose positron emission tomography (FDG-PET) is also useful for identifying the viable portion of the tumor (Fig 19-3). Vascular lesions such as aneurysms or arterial venous malformations can be easily recognized on contrast-enhanced CT.

Figure 19-1 Anterior approach to a lesion in the left upper lobe. The patient was placed in a slightly oblique position, and an oblique anterior approach was chosen to avoid bullae surrounding the mass.

Figure 19-2 Prone biopsy of a cavitary lesion. A, New left upper lobe cavitary nodule was identified in a patient with treated nodular sclerosing Hodgkin’s lymphoma. B, The biopsy specimen from the wall of the cavity showed coccidioidomycosis.

Figure 19-3 A, FDG-PET of a lung mass reveals viable metabolically active tumor only at the periphery. B, CT-guided biopsy, with a specimen obtained from the periphery, revealed non–small cell lung cancer.

Imaging Guidance

Fluoroscopy or CT can be used for imaging guidance. Ultrasound is occasionally used for chest wall or peripheral lesions abutting the pleura. Fluoroscopically guided biopsies are usually reserved for large masses (Fig. 19-4). Fluoroscopy allows real-time, moment-to-moment visualization and often enables the biopsy to be performed in less time than that required for a CT-guided biopsy. However, we prefer to use CT for imaging guidance in all transthoracic needle biopsies. It allows a more complex approach, and safe and accurate sampling of hilar or mediastinal masses is possible. CT also provides better visualization of severe emphysematous areas or bullae, which may lie within the path of a needle. Real-time, continuous CT fluoroscopy combines the advantages of standard fluoroscopy with CT guidance.

Figure 19-4 A and B, Fluoroscopically guided biopsy of a large right lower lobe mass. A C-arm or biplane fluoroscopic unit should be used for these procedures.

Needle Selection

A variety of needles can be used for TNB. Small-bore, 18- to 22-gauge needles are preferred because larger-bore needles have been associated with high complication rates, particularly bleeding and pneumothorax. Aspirating needles commonly used include Chiba and Greene varieties. These needles provide only cytologic material from aspirates. Automatic biopsy devices that provide small cores of tissue, sometimes referred to as biopsy guns, are available. The length of the needle selected should be greater than the depth of the lesion from the skin and preferably 3 to 5 cm longer. If coaxial technique is used, the inner needle length should be 5 cm longer than the introducer needle.

On-Site Pathology

The high diagnostic accuracy of TNB can be attributed to improved radiologic techniques such as CT guidance and, even more importantly, to advances in cytologic techniques and interpretation. The TNB technique should be a cooperative effort between the cytologist and the radiologist. We prefer to have a cytologic technician available during the biopsy. Quick stains can be performed, and a cytologist can be called to provide a rapid interpretation of the specimen. This allows for repeat biopsy if the specimen is nondiagnostic or inadequate and permits the use of core-needle specimens as a supplement to the aspiration when the diagnosis cannot be obtained from the aspirated sample.

Technical Factors

The shortest, most vertical biopsy path should be chosen based on the prebiopsy CT scan (Fig. 19-5). Interlobar fissures, pulmonary vessels, bullae, and areas of severe emphysema should be avoided (see Fig. 19-1). Sometimes, this can be achieved by tilting the CT gantry (Fig. 19-6). Paraspinal and extrapleural saline injection creates safer access to paramediastinal lesions (Fig. 19-7). The patient is placed in a position that provides a safe approach—prone, supine, or occasionally, decubitus—as indicated. After a scanogram is performed, thin-section, 2- to 5-mm CT slices are obtained through the lesion with a localizing grid in place on the skin overlying the lesion. A desired skin puncture site is identified using the grid, and the patient is prepared and draped in a sterile manner. After the injection of local anesthesia, a small puncture is made in the skin and subcutaneous tissues with a scalpel.