EUS-guided fine-needle aspiration in the mediastinum.

The evaluation and management of esophageal and mediastinal disease has changed considerably since the introduction of EUS. EUS provides precise imaging of the histologic layers of the esophageal wall and surrounding mediastinal structures. EUS is now a well-established modality for the staging of a variety of GI and pancreaticobiliary malignancies. Furthermore, it has been reported to play an important role in the evaluation of mediastinal lesions and in the detection of metastasis to lymph nodes.1-9 Traditionally, the mediastinum has been evaluated by radiographic imaging such as CT and by invasive studies like bronchoscopy and mediastinoscopy. Evaluation of the mediastinum using EUS has been reported to be useful for a number of indications. Most notable is the assessment of enlarged lymph nodes that are detected by other imaging modalities such as CT or magnetic resonance imaging. Probably the most important indication for mediastinal imaging is the detection and/or staging of lung cancer. Documentation of lymph node involvement with metastatic disease is crucial in the staging and management of non-small cell lung cancer (NSCLC). The introduction of the curved linear array echoendoscope approximately 8 years ago led to the development of EUS-guided fine-needle aspiration (FNA), which is now becoming recognized as an integral part of endosonography. EUS-guided FNA has been reported to be a safe and effective approach for evaluation of lymph nodes and masses in the posterior mediastinum.10-13 Tissue diagnosis from these lesions has been difficult to obtain by conventional methods such as mediastinoscopy, which is an invasive and tedious procedure, or percutaneous CT-guided puncture, which has a low yield and increased risk, especially in the case of smaller lesions.14 The objectives of this article are twofold: to discuss the clinical utility of EUS and EUS-guided FNA biopsy for evaluating the mediastinum in benign and malignant disease processes including the detection of posterior mediastinal lymph node metastases in patients with NSCLC and to describe the technique for performing safe EUS-guided FNA biopsy in the mediastinum.