The tumor was characterized of positive immunohistochemical reaction for antibodies to cytokeratin CAM 5.2, cytokeratin 20 CK20 (Figure 3: immunoperoxidase staining for CK20 showing positive tumor cells, original magnification ×400), neurofilaments NF (Figure 4: immunoperoxidase staining for NF showing positive tumor cells, original magnification ×400) and neuroendocrine markers chromogranin, synaptophysin and CD56. Here, KRT20 is linked to neoplasm.