MKI67 and hereditary pheochromocytoma-paraganglioma: Ancillary use of many immunohistochemical markers showed some significance and association with the malignant potential of these tumors, such as the proliferative index Ki67, S100 to determine the number of sustentacular cells, and succinate dehydrogenase B (SDHB) for screening patients with hereditary paraganglioma pheochromocytoma syndrome (loss of expression of SDHB may indicate malignant biological potential) [1,14,21].