Tumour seeding after transbronchial biopsy: Mechanisms, clinical implications, and prevention strategies-A narrative review.

Tumour seeding, defined as the inadvertent transplantation and proliferation of malignant cells during diagnostic or therapeutic procedures, is a rare but clinically significant complication of transbronchial biopsy (TBB). TBB includes conventional forceps biopsy (CFB), endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA), and cryobiopsy, and is widely used for diagnosing pulmonary and mediastinal lesions. As bronchoscopic procedures become increasingly important for early-stage cancer diagnosis, understanding this rare event is essential. This review synthesised evidence from PubMed, Google Scholar, Embase, and Scopus (January 2000 to August 2025) on TBB-related seeding, following established narrative review methodology. A total of 58 publications, including case reports, case series, and reviews, were analyzed. Only four well-documented cases of tumour seeding were identified, highlighting the extreme rarity of this complication. Seeding developed one week to four months after TBB, most often involving adenocarcinoma or squamous cell carcinoma. The true incidence remains unknown but was considered far lower than that of percutaneous biopsy approaches (0.6-2.7% for transthoracic needle aspiration). True incidence cannot be reliably calculated from case reports alone; however, bronchoscopic approaches appeared substantially safer than transthoracic needle aspiration. Mechanistic risk factors are largely extrapolated from non-bronchoscopic biopsy procedures owing to limited TBB-specific data. Despite scarce evidence, enhanced awareness, informed consent and systematic surveillance are recommended as the diagnostic benefits of TBB clearly outweighed the minimal seeding risk. Future multicentre registries with long-term follow-up are crucial for better quantifying incidence and informing evidence-based preventive strategies.