Huge primitive neuroectodermal tumor of the pancreas: Report of a case and review of the literature

Figure 2 Histomorphological characteristics and immuno-labeling of PNET. A: Solid tumor cell sheets separated by a delicate fibrovascular stroma; B: Strong membranous expression of CD99 (MIC-2) in the entire tumor cell population; C: Vimentin-positive neoplastic cells; D: Expression of cytokeratins (KL-1) in a minor tumor cell subset; E: Partial CD56-positive neoplastic population; F: Nuclear staining for the Ki67 proliferation antigen (MIB-1) in about 20%-30% of tumor cells.