Specifically the Grading System for Adrenal Pheochromocytoma and Paraganglioma (GAPP) criteria include six variables: histological pattern, cellularity, comedo-type necrosis, capsular/vascular invasion, Ki67 labelling index and catecholamine type (36) or the PASS score (37) based on 12 histologic features such as diffuse growth, high cellularity, cellular monotony, tumor cell spindling, mitotic figures [3/10 HPF, atypical mitoses, profound nuclear pleomorphism and nuclear hyperchromasia. The gene discussed is MKI67; the disease is paraganglioma.