C. Dooms MD, PhD, B. Weynand MD, PhD, S. Vander Borght PhD, L. Vliegen MSc, E. Verbeken MD, PhD, J. Vansteenkiste MD, PhD, P. Vandenberghe MD, PhD
Endobronchial ultrasonography is a minimally invasive endoscopic technique that enables a real time transbronchial needle aspiration. Endobronchial ultrasound guided transbronchial needle aspiration (EBUS-TBNA) specimens have a high diagnostic accuracy in the detection of intrathoracic lymph node metastasis for a variety of malignancies. Predictive biomarker testing is gaining wide importance to tailor the treatment with the largest benefit to the patient. Endobronchial ultrasound guided transbronchial needle aspiration also results in an accurate analysis of molecular alterations (by ImmunoHistoChemistry, Fluorescence In Situ Hybridisation, or gene sequencing) provided that the endoscopist takes sufficient tumour samples and a dedicated cytopathologist is involved in the mastery of the specimens.
Endobronchial ultrasound guided transbronchial needle aspiration samples can be handled in different ways. Liquid-based cytology and smears are mostly used. The choice of the testing method should be based primarily on the nature of the sample to be tested, testing laboratory’s expertise, and available equipment. ImmunoHistoChemistry, Fluorescence In Situ Hybridisation and targeted polymerase chain reaction-based sequencing can be performed on >80% of the endobronchial ultrasound guided transbronchial needle aspiration specimens, as the latter is more sensitive in terms of limit of detection than Sanger sequencing. The next step are the next generation sequencing assays, with only 10–20 ng of DNA sample input per gene mutation, which will minimise rejected samples due to insufficient sample quantity.