CHGA and neoplasm: The immunohistochemical method allows us to estimate the proliferative activity of the neoplasm by the expression of the Ki-67 proliferation marker and the factor regulating the cell cycle–CyclineD1 (CycD1), the presence of endocrine cells in the parenchymatous component of RC by the expression of Chromogranin A (ChrgA), to estimate apoptosis by the expression of the transcription factor p53 and apoptosis regulator–protein Bcl2 [4,5].