Endoscopic Ultrasound in the Diagnosis of Sarcoidosis: A Forgotten Tool?

To the Editor:

With keen interest, we read the guidelines for the diagnosis and detection of sarcoidosis by Crouser and colleagues in a recent issue of the Journal (1). We congratulate the authors for achieving this daunting task of formulation of guidelines for sarcoidosis. The authors have extensively elaborated on the role of endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) in the diagnosis of sarcoidosis. However, the document lacks the discussion on the utility of fine-needle aspiration using endoscopic ultrasound (EUS-FNA) as well as endoscopic ultrasound using echobronchoscope (EUS-B-FNA).

EUS-FNA is a real-time fine-needle aspiration procedure, through the esophagus, providing access to left paratracheal, subcarinal, and paraesophageal lymph node stations. It is a highly sensitive, accurate, fast, safe, and minimally invasive method. Its diagnostic yield for sarcoidosis varies between 77% and 94% (2, 3). Randomized trials comparing EBUS-TBNA and EUS-FNA have either shown a similar yield or a higher yield of EUS-FNA (4, 5). EUS-B-FNA has also been demonstrated to have a comparable yield as EBUS-TBNA in a randomized trial (6). The sensitivity of the endosonography for diagnosing sarcoidosis was 85% overall, 84% for EBUS-TBNA, and 87% for EUS-B-FNA. Oki and colleagues also demonstrated a diagnostic yield of 86% with EUS-B-FNA in 29 patients for the diagnosis of stage I and II sarcoidosis (3). The procedure is better tolerated in patients with reduced lung function and intractable cough. The reduced need for sedatives and topical anesthesia as well as reduced procedure duration are the added advantages of EUS-B-FNA compared with EBUS-TBNA (6). The training required for EUS-B-FNA is also minimal for a trained interventional pulmonologist, and the procedure can be performed using the same echobronchoscope circumventing the additional expenditure of involving a gastroenterologist.

Meta-analysis comparing overall diagnostic yield and safety of EUS-B-FNA combined with EBUS-TBNA in the diagnosis of mediastinal lymphadenopathy demonstrated an additional diagnostic gain of 7.6% in EUS-B-FNA over EBUS-TBNA (7). The procedure is also considered safe, and a meta-analysis demonstrated a complication rate of 0.30% after EUS as compared with 0.05% in the EBUS group. Most of the reported complications were in patients with lung cancer, and the complication rate was even lower for sarcoidosis (8). The advantage of EBUS-TBNA over EUS-B-FNA is its higher reach for mediastinal lymph node stations so that a multistation sampling can be done.

Keeping these points in mind, we are of the view that sampling of mediastinal lymph nodes for the diagnosis of sarcoidosis may be performed with either EBUS-TBNA or EUS-(B)-FNA depending on the operator’s comfort, the patient’s general status, involved lymph node stations (7 and 4L), and equipment availability.