Macroscopic on-site evaluation for stratifying the incremental diagnostic benefit of additional sampling during endobronchial ultrasound-guided transbronchial needle aspiration.

OBJECTIVES: Macroscopic on-site evaluation (MOSE) enables immediate gross assessment of aspirated specimens during endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA). However, its role in stratifying the benefit of selective additional sampling remains unclear. We aimed to evaluate whether MOSE could identify patients in whom additional sampling provides meaningful incremental diagnostic benefit. METHODS: This single-center retrospective observational study included consecutive patients who underwent diagnostic EBUS-TBNA between April 2023 and December 2025. MOSE was defined as the gross identification of tissue material during specimen preparation and was categorized as positive or negative at the target lesion level. The diagnostic yield of EBUS-TBNA and the incremental diagnostic benefit of additional sampling, including endobronchial ultrasound-guided intranodal forceps biopsy and cryobiopsy, were evaluated according to MOSE status. RESULTS: A total of 185 patients were included. MOSE was positive in 137 patients (74.1%) and negative in 48 patients (25.9%). Overall diagnostic yield was significantly higher in MOSE-positive than in MOSE-negative patients (94.9% vs. 64.6%, P < 0.001). When restricted to EBUS-TBNA alone, diagnostic yield remained significantly higher in MOSE-positive than in MOSE-negative patients (93.4% [128/137] vs. 47.9% [23/48], P < 0.001). The incremental diagnostic benefit of additional sampling was significantly greater in MOSE-negative than in MOSE-positive patients (16.7% [8/48] vs. 1.5% [2/137], P < 0.001). CONCLUSION: MOSE may serve as a practical real-time indicator for identifying patients in whom additional sampling is most likely to provide incremental diagnostic benefit during EBUS-TBNA, thereby supporting more selective and efficient sampling strategies.