RESUMEN
Personalized treatment of metastatic non-squamous non-small cell lung cancer (NSCLC) requires detailed molecular characterization of the tumour including detection of predictive driver mutations and programmed death ligand 1 (PD-L1) expression. Complete detection is influenced by the amount of tumour cells sampled as well as their quality. Different sampling techniques may be necessary to provide sufficient tumour material for comprehensive molecular characterization. Missing the detection of targetable molecular genetic aberrations would have a serious impact on the quality of life and prognosis of a patient. This case report highlights the importance of biopsy technique in a patient with NSCLC. Several procedures-pleural puncture, transthoracic lung biopsy and endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA)-could not provide sufficient tumour material for precise tumour characterization. Only the addition of EBUS-guided transbronchial lymph node cryobiopsy (EBUS-TBLNC) enabled complete immunohistochemical and genetic tumour characterization, demonstrating PD-L1 expression in 100% of the tumour cells in the absence of actionable genetic alterations. Based on these results, immunotherapy was initiated.