Figure 1

PPGLs express low levels of Ki-67 and HIF-1α. (A) Representative images from tumor cores scored as negative (0), weak (1 +), intermediate (2 +) or strong (3 +) for Ki67. (B) Quantification of Ki67 positive cells (in %). (C) Representative images from tumor cores scored as negative (0), weak (1 +), intermediate (2 +) or strong (3 +) for HIF-1α. (D) Quantification of HIF-1α positive cells (in %). Tumor cores were scored manually by three independent researchers as well as semi-automatically using the QuPath-0.3.0 software. Statistical significance was determined by the Mann–Whitney test. sPGL, sympathetic paraganglioma; HN-PGL, head- and neck paraganglioma; PCC, pheochromocytoma. The scale bar represents 100 μm in core images and 50 μm in zoomed images.