PRIMITIVE NEUROECTODERMAL TUMOR ARISING IN THE PANCREAS

Peripheral primitive neuroectodermal tumors (PNETs) are extra cranial primitive small round blue cell tumors showing histologic, immunohisto chemical or electron microscopic evidence of neuroectodermal different iation. They are most commonly encountered in the soft tissue or bone in children and young adults. We report an unusual case of a PNET aris ing in the pancreas. A 17yr-old male presented with a pancreatic mass and underwent a pancreatoduodenectomy. Histologically, the neoplasm wa s composed of sheets of small round cells that stained for cytokeratin , neuron specific enolase, and 12E7 but not muscle specific actin, des min, common leukocyte antigen, chromogranin, synaptophysin, or other i slet cell markers. The diagnosis of PNET in this unusual location was confirmed by cytogenetic analysis which showed the chromosomal translo cation characteristic of PNETs, t(11;12)(q24;q12). This case highlight s the difficulty in the diagnosis of PNET when it is present in viscer al organs where other neuroendocrine neoplasms and adenocarcinomas are more common.