MKI67 and adenoma: The adenocarcinomas could be distinguished from the adenomas by their larger size (>5-10 mm in diameter) and positive staining for Pcna (Figure 2A and 2B) (∼90% positive in adenocarcinomas versus ∼10-12% in adenomas) and Ki-67 (40-45% positive in adenocarcinomas versus 5-8% in adenomas) (Figure 2C and 2D).