Many studies have tried to find biomarkers to differentiate between benign and malignant PCC/PGL, such as the Ki67 labeling index, human telomerase reverse transcriptase (hTERT) or CD44 expression.[13,14] However, none of these markers allows a definite diagnosis of malignancy in PCC/PGL. Here, MKI67 is linked to adrenal gland pheochromocytoma.