Contrast-enhanced CT and MRI findings of pancreatic Ewing sarcoma in a pediatric patient: a case report

Pancreatic Ewing sarcoma, a rare tumor in pediatric patients, is a diagnostic challenge from an imaging perspective. We report abdominal contrast-enhanced computed tomography (CT) and magnetic resonance imaging (MRI) findings of a retroperitoneal mass in an 11-year-old girl with abdominal pain, nausea, vomiting, a weight loss of approximately 14 kg, and a palpable epigastric mass on physical examination. A contrast-enhanced CT showed a heterogeneous 7.9 x 6.8 x 10.6 cm mass with necrotic areas in the body of the pancreas displacing adjacent organs and contacting vascular structures with adequate interphase without infiltrating them. Lymph nodes were not observed. The origin of the mass within the circumscribed margin at the level of the pancreatic body was seen on MRI: hypointense in T1, with increased heterogeneous signal intensity in T2 and with hypointense areas in the center, suggesting necrosis, without infiltration of adjacent structures, dilatation of the pancreatic duct or nodal involvement. A biopsy was performed by laparotomy. Immunohistochemical CD99 staining showed intense and diffuse expression of tumor cells in the cytoplasmic membrane, confirming the primitive neuroendocrine tumor. The histopathologic diagnosis was Ewing sarcoma of the pancreas. This is the first case report of imaging findings in Mexico and is published for educational purposes.