Lung Adenocarcinoma with Bilateral Renal Metastases

This case highlights the clinical and pathological features of a TTF-1-/Napsin A-negative lung adenocarcinoma. It underscores the systematic diagnostic workup required to confirm a lung primary in this challenging context, illustrates the correlation between this specific tumor phenotype and its aggressive clinical behavior with widespread metastases, and emphasizes the central role of comprehensive biomarker testing in the modern management of advanced NSCLC.