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

Abstract

Primitive neuroectodermal tumor (PNET) of the pancreas is an extremely rare tumor that usually occurs in children or young adults. We report a case of a 33-year-old male patient with an 18 cm multiply 18 cm multiply 16 cm mass arising from the pancreatic body and tail with a one-day history of abdominal pain. Initial CT scan showed no signs of metastatic tumor spread. The tumor caused intrabdominal bleeding and the patient underwent primary tumor resection including partial gastrectomy, left pancreatic resection and splenectomy. Diagnosis of PNET was confirmed by histology, immunohistochemistry and FISH analysis. All neoplastic cells were stained positive for MIC2-protein (CD99). Approximately one month after surgery, several liver metastases were observed and the patient underwent chemotherapy according to the Euro-Ewing protocol. Subsequent relaparotomy excluded any residual hepatic or extrahepatic abdominal metastases. Although PNET in the pancreas is an extremely rare entity, it should be considered in the differential diagnosis of pancreatic masses, especially in young patients. This alarming case particularly illustrates that PNET in the pancreas although in an advanced stage can present with only a short history of mild symptoms.

Figure 1

CT-scan showing a huge intra-abdominal mass with solid and cystic areas originating from the pancreas.

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.