The study aims to compare the efficacy and safety of endobronchial ultrasound-guided transtunnel forceps biopsy to transbronchial needle aspiration in diagnosing inadequate lymph node specimens based on macroscopic on-site evaluation.

Mediastinal and hilar lymphadenopathy are common clinical conditions. Endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) is the standard method recommended by guidelines for obtaining tissue from these patients. Endobronchial ultrasound-guided transbronchial forceps biopsy (EBUS-TBFB) can overcome the limitations of inadequate tissue acquisition with EBUS-TBNA, and its efficacy and safety have been proved. However, EBUS-TBFB often requires the assistance of the electrocautery for mediastinal window creation, which increases technical difficulty and requires electrosurgical equipment, making it unsuitable for application in grassroots hospitals.

This study aims to use the endobronchial ultrasound-guided transtunnel forceps biopsy (EBUS-TTFB) method. A single-use bronchoscopic puncture dilation catheter will be employed to establish a tunnel between the airway and the lymph node, with both puncture and dilation completed in the same procedure. Currently, there is a lack of prospective randomized controlled trials to verify the efficacy and safety of EBUS-TTFB.

This study is designed as a prospective, multicenter, randomized controlled trial. A total of 162 patients will be randomly allocated in a 1:1 ratio to the EBUS-TBNA group or the EBUS-TTFB group. The primary endpoint is thediagnostic yield. The secondary endpoints include specimen adequacy, procedure duration, tunnel creation success rate, and safety.

Inclusion Criteria:

1. Age ≥ 18 years;
2. Chest imaging shows mediastinal or hilar lymphadenopathy (short axis ≥10 mm), requiring EBUS-TBNA for definitive diagnosis;
3. EBUS-TBNA can be performed on these lymph nodes, and the specimens obtained from conventional EBUS-TBNA with three needle passes are inadequate (macroscopic visible core < 30 mm);
4. Willing to participate in this clinical study and sign the informed consent form.

Exclusion Criteria:

1. Enlarged lymph nodes are identified as cystic or abscesses;
2. Severe coagulopathy, insufficient anticoagulants/antiplatelets withdraw time or bleeding diathesis (platelets<50*109/L, INR>1.3) that do not meet bronchoscopy requirements;
3. Other contraindications to bronchoscopy or transbronchial biopsy, such as severe cardiopulmonary insufficiency, intolerance to anesthesia, or endoscopic procedures;
4. Patients who have participated in another clinical trial within the past three months;
5. Vulnerable groups, such as pregnant women
6. Any other condition that the investigator considers inappropriate for participation in this study.