8 - Endoscopic ultrasound in the evaluation of posterior mediastinal lesions and lung cancer

Abstract

Endoscopic ultrasonography-guided fine-needle aspiration (EUS FNA) or fine-needle biopsy (EUS FNB) is used to evaluate masses and lymphadenopathy of the posterior mediastinum and in the staging and diagnosis of lung cancer. The differential for lesions of the posterior mediastinum includes neoplastic lesions such as lung cancer, lymphoma, esophageal cancer, neurogenic tumors, leiomyomas, and metastases from distant tumors. Nonneoplastic etiologies of mediastinal lymph nodes and masses include duplication cysts, tuberculosis, histoplasmosis, and sarcoidosis. EUS FNA has a high accuracy in distinguishing these different etiologies. Core biopsy needles provide a method to obtain larger biopsies to provide architectural information to distinguish lymphoma subtypes. Duplication cysts are mediastinal cysts which can often be distinguished from solid masses by the presence of acoustic enhancement. A potential complication of EUS FNA in the mediastinum is mediastinitis, particularly with cystic lesions. EUS FNA of mediastinal lesions is a safe procedure with a low rate of adverse events. EUS FNA and endobronchial ultrasound (EBUS) with transbronchial needle aspiration (TBNA) are the techniques of choice for the diagnosis and staging of non–small cell lung cancer and reduce the number of mediastinoscopies and unnecessary thoracotomies. In addition to staging of mediastinal lymph node stations in lung cancer, EUS can sample intrapulmonary tumors adjacent to the esophagus, assess for mediastinal invasion, and access lower mediastinal lymph node stations.