A Rare Location for a Rare Gastrointestinal Tumor With a Classical Presentation of Abdominal Pain, and Gastrointestinal Bleeding: 2523

INTRODUCTION: Yolk sac tumors belong to the class of nonseminomatous germ cell tumor (NSGCT), which rarely present as extragonadal germ cell tumors (GCT) of the retroperitoneum. Patients present with small bowel obstruction or gastrointestinal bleeding. Most commonly, these retroperitoneal tumors affect the ileum or jejunum, but here we present a case of a 31-year-old man who presented with a retroperitoneal yolk sac tumor with associated fistulization to the duodenum, jejunum, and ileum. CASE DESCRIPTION/METHODS: A 31 year-old man with no medical or surgical history was admitted with abdominal pain and melena. He underwent contrast-enhanced abdominal computed tomography (CT) showing an enlarging mass with central necrosis, and small bowel fistulization. Gastroenterology was consulted and upper endoscopy was performed, showing evidence of a duodenal mass and fistula, which was biopsied. Initial biopsies were inconclusive. Surgical oncology was consulted, and the patient underwent attempted surgical resection but the majority of the small intestine, colon, and associated mesentery were tethered and resection was not possible. A repeat EGD-guided biopsy was performed and pathology had the histological and immunohistochemical features of a yolk sac tumor. Laboratory studies revealed elevated serum alpha-fetoprotein (AFP) of 992 ng/mL [<6.0 ng/mL], normal serum beta-human chorionic gonadotropin (beta-hCG), and elevated serum lactic acid dehydrogenase (LDH) of 421 U/L [122-222 U/L]. Testicular ultrasound was negative for any abnormalities. Oncology initiated the patient on neoadjuvant cisplatin, etoposide, and bleomycin (BEP) every three weeks for three cycles. Two weeks after starting first cycle, AFP had dropped to 65 ng/mL, and thereafter to 11 ng/mL. Repeat imaging showed that the tumor had decreased in size. Approximately three months after completion of the last cycle of chemotherapy the patient underwent retroperitoneal tumor resection, along with partial small bowel resection. There was no evidence of malignancy in the final surgical pathology. One year later he is cancer free. DISCUSSION: This case highlights a successful collaboration between gastroenterology, radiology, surgery and oncology. There are no randomized trials in the treatment of retroperitoneal GCTs, thus case reports such as this provide much needed guidance in the treatment of this rare condition. It also illustrates the importance of tissue diagnosis via EGD in order to provide prompt diagnosis without invasive surgical biopsy.