Transbronchial mediastinal cryobiopsy in the diagnosis of mediastinal lesions: a randomised trial

Guidelines recommend endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) as an initial investigatory technique for mediastinal nodal staging in lung cancer. However, EBUS-TBNA can be limited by the inadequacy of intact tissues, which might restrict its diagnostic yield in mediastinal lesions of certain aetiologies. We have previously shown that EBUS-guided transbronchial mediastinal cryobiopsy can provide intact samples with greater volume.

This randomised study determined the diagnostic yield and safety of transbronchial mediastinal cryobiopsy monitored by endosonography for the diagnosis of mediastinal lesions. Patients with a mediastinal lesion of ≥1 cm in the short axis were recruited. Following identification of the mediastinal lesion by linear EBUS, fine-needle aspiration and cryobiopsy were sequentially performed in a randomised order. Primary end-points were diagnostic yield, defined as the percentage of patients for whom mediastinal biopsy provided a definite diagnosis, and procedure-related adverse events.

In total, 197 patients were enrolled and randomly allocated. The overall diagnostic yield was 79.9% and 91.8% for TBNA and transbronchial mediastinal cryobiopsy, respectively (p=0.001). Diagnostic yields were similar for metastatic lymphadenopathy (94.1% versus 95.6%, p=0.58), while cryobiopsy was more sensitive than TBNA in uncommon tumours (91.7% versus 25.0%, p=0.001) and benign disorders (80.9% versus 53.2%, p=0.004). No significant differences in diagnostic yield were detected between "TBNA first" and "Cryobiopsy first" groups. We observed two cases of pneumothorax and one case of pneumomediastinum.

Transbronchial cryobiopsy performed under EBUS guidance is a safe and useful approach that offers diagnostic histological samples of mediastinal lesions.