Endoscopic Ultrasound-Guided Transoesophageal Biopsy in a Mediastinal Tumour: A Case Report.

Endoscopic ultrasound-guided transoesophageal biopsy (EUS-FNA/FNB) is a minimally invasive and highly accurate diagnostic technique for evaluating mediastinal lesions, particularly in centres where surgical approaches or endobronchial ultrasound are unavailable. We report the case of a 79-year-old woman with multiple comorbidities who presented with non-specific abdominal pain and a 5 kg weight loss over 1 month. Imaging revealed a 50% left pleural effusion and mediastinal and retroperitoneal lymphadenopathy. Endoscopic ultrasound demonstrated hilar, retroperitoneal and interaortocaval lymph nodes, prompting a transoesophageal fine-needle biopsy using a 22G needle and fanning technique, which was performed without complications. Initial histopathology suggested a lymphoproliferative process, and a subsequent excisional lymph node biopsy confirmed classical mixed-cellularity Hodgkin lymphoma associated with Epstein-Barr virus. This case highlights the diagnostic value of EUS-FNA/FNB in mediastinal lesions that are difficult to access using traditional techniques. Although its diagnostic yield is high, lymphomas-particularly Hodgkin lymphoma-may require additional tissue sampling to preserve architectural detail. Procedure success depends on sample adequacy, needle selection and operator expertise. Integrating EUS-guided biopsy into a multidisciplinary diagnostic pathway enables safe, effective and timely evaluation of mediastinal pathology, especially in resource-limited settings or in patients with significant comorbidities.