Recurrent Primitive Neuroectodermal Tumor (PNET) of the Pancreas

Abstract

Ewing's family of tumors (EFT) originate from neuronal crest cells and share morphological, histological and cytogenic features. EFTs include typical (osseous) Ewing's sarcoma, atypical (non-osseous) Ewing's sarcoma, primitive neuroectodermal tumor (PNET), and Askin tumor. Only a few cases of ES/PNETs of the pancreas have been reported and even fewer cases of recurrent pancreatic PNETs are known. Herein we report a case of recurrent pancreatic PNET presenting as abdominal pain ten years following treatment of left scapular Ewing's sarcoma. Four years following partial resection, local radiation and CHOP chemotherapy for left scapular Ewing's sarcoma, a 54-year-old male presented with epigastric abdominal pain. CT scan of the abdomen demonstrated a mass at the head of the pancreas and biopsy confirmed a CD-99 positive round blue cell tumor. FISH showed 15 % ESWR1 locus rearrangement. Together these findings were consistent with pancreatic PNET. The patient was treated with local radiation and CHOP chemotherapy. Treatment response was monitored with serial PET scans. Unfortunately, after six years of sustained response the patient presented with epigastric abdominal pain. Laboratory studies were significant for elevated bilirubin (1.1 mg/dL). A mesenteric vein thrombosis was detected on CT scan as well as a 43 mm by 29 mm mass at the pancreatic head. PET scan confirmed a 19 mm by 22 mm FDG avid area at the head of the pancreas. Biopsy demonstrated a CD-99 positive round blue cell tumor. Overall the findings were consistent with recurrent pancreatic PNET.EFT/PNETs are round blue cell tumors with neuroendocrine differentiation (chromogranin A, synaptophysin or neuron specific enolase) and CD-99 expression. Although, CD-99 is nonspecific. Additionally, many EFTs demonstrate t(11; 12) (q24; q12) chromosomal translocation resulting in the fusion protein EWS-FLI1 which disrupts transcription and drives tumor growth. EFTs commonly arise from long bones and afflict young patients. Although rare, EFT/PNETs can arise from solid organs. Primary PNETs of the lung, urinary bladder, gall bladder, and uterus have been reported. Only 0.3 % of pancreatic masses are diagnosed as EFT/PNET. Our case highlights the importance of correlating clinical, radiographic, and pathological findings in the diagnosis of pancreatic PNET and emphasizes the importance of multimodality treatment of this aggressive disease.