The discrepant results between TMA and large section IHC were observed in a pancreatic NET G3 and attributable to suboptimal immunoreactivity of major tumor areas, which—for PMS2—resulted in still faintly detectable staining of stromal cells but negativity of tumor cells on the TMA spot in contrast to unequivocally retained MMR protein expression in cancer cells on large section. This evidence concerns the gene MRC1 and pancreatic neuroendocrine tumor.