Fig. 1

Study design. A A total of 400 patients with lung-specific CUPs were screened. Major exclusion criteria included definitive diagnosis by imaging, histopathologic, or molecular findings, inadequate tissue samples, and incomplete follow-up data. Sixteen patients were finally included in our study. CUP, cancer with unknown primary. B Representative findings from a case (P1) for which conventional diagnostic work-up did not reach a definitive diagnosis. Original magnification ×200. CT: computed chromatography. H & E: hematoxylin and eosin