Primary pancreatic Ewing sarcoma with metastases on FDG PET/CT

Abstract

Background Ewing sarcoma (ES) is a highly aggressive malignant tumor most commonly affecting long bones. Extraskeletal Ewing sarcoma (EES) is a malignant tumor with aggressive behavior carrying bad prognosis with pancreas being an extremely rare primary site. We present a case of histopathologically proven EES of the pancreas in a young female who presented with abdominal pain. 18F-fluorodeoxyglucose positron emission tomography (18F FDG PET/CT) is a useful modality for detecting distant metastases in EES. It helps in diagnosis, localizing the primary, its extension, optimal treatment planning and evaluation of response to standard treatments available. Case presentation An 18-year-old female presented with complaints of progressive abdominal pain and distention since 6 weeks. Physical examination was suggestive of a solid large mass in the upper left abdomen and decreased breath sounds with dullness in the left lower lung fields. On Contrast enhanced computed tomography (CECT) imaging, a large heterogeneously enhancing mass was seen arising from pancreas along with retroperitoneal lymphadenopathy. A moderate sized left sided pleural effusion with atelectasis of lower lobe of left lung was also noted. Histopathological analysis was suggestive of pancreatic ES following which the patient underwent five cycles of chemotherapy. Following this, she underwent 18F FDG PET/CT which showed hypermetabolic large mass arising from body and tail of pancreas with areas of internal necrosis along with left adrenal metastasis, retroperitoneal lymphadenopathy, a massive left pleural effusion and compressive atelectasis of left lower lobe. The patient expired within a week following PET/CT. Conclusions EES most often presents in the late stage of the disease with vague symptoms. Timely diagnosis and initiation of treatment is of utmost importance considering the aggressiveness of the tumor. Establishing a diagnosis of Ewing sarcoma is especially difficult when the mass is arising from the pancreas. Imaging, histopathology and immunohistochemistry (IHC) play a key role in accurate diagnosis of such masses. 18F FDG PET/CT can be useful for detecting local and distant spread, operability, treatment planning and evaluation of response to chemotherapy.