Endobronchial Ultrasonography in the Diagnosis of Sarcoidosis

Overview

Sarcoidosis is a benign, inflammatory condition which will typically involve the lungs and lymph glands in the chest. Diagnosis is often confirmed with bronchoscopic biopsy. A new method of performing bronchoscopic biopsy of lymph glands in the chest has now been developed which uses real-time endobronchial ultrasonography to better locate the lymph glands. While this technique has been proven to be effective in the diagnosis and staging of lung malignancy, its sensitivity for the diagnosis of sarcoidosis is unclear as smaller samples are obtained compared to the standard approach. This study will aim to randomize 50 patients with a clinical suspicion of sarcoidosis to standard biopsy vs. endobronchial ultrasound guided biopsy of the mediastinal lymph glands in order to compare the sensitivity of these tests for sarcoidosis.

Sarcoidosis is a benign, inflammatory condition which will typically involve the lungs and mediastinal lymph nodes. The diagnosis of sarcoidosis is usually confirmed with tissue biopsy, especially if patients in whom treatment with corticosteroids is required. Asymptomatic patients not requiring treatment may not require biopsy, although this is commonly performed because of patient's preference in confirming the diagnosis and concerns about other diagnostic possibilities such as lymphoma. Given the predilection of this disease to the chest, the lung and mediastinal lymph nodes are the most common sites for biopsy. Bronchoscopic samples are often obtained initially given their good sensitivity for this disease and low complication rates. If the diagnosis of sarcoidosis is not confirmed by bronchoscopy, more invasive surgical procedures such as mediastinoscopy or open lung biopsy may be required. As such, any improvement in the minimally invasive methods for diagnosis of this condition would be of benefit these patients and may also lead to cost efficiencies for the health care system. Transbronchial needle aspiration (TBNA) with a 19 gauge "histology" needle has been the standard bronchoscopic approach to the biopsy of mediastinal lymph nodes in patients with suspected sarcoidosis. Using anatomical landmarks and computed tomography (CT) images, the TBNA needle is advanced "blindly" through the airway wall, and into the mediastinal lymph node. Because of the lack of real-time visual guidance, it is possible to miss the targeted lymph node as well as enter vascular structures with the needle system and cause bleeding. A new method of performing TBNA has now been developed which uses real-time endobronchial ultrasonography to advance a 22 gauge needle into mediastinal lymph nodes under direct visualization (EBUS-TBNA). While this technique has been proven to be effective in the diagnosis and staging of lung malignancy, its sensitivity for the diagnosis of sarcoidosis is unclear given that larger biopsy samples are often required to make this diagnosis. This study will aim to randomize patients with a clinical suspicion of sarcoidosis and mediastinal adenopathy undergoing bronchoscopy to TBNA vs. EBUS-TBNA in order to compare the sensitivity of these tests for sarcoidosis.