Duodenal mature teratoma causing partial intestinal obstruction:A first case report in an adult

BACKGROUND A teratoma is a germ cell tumor that is composed of tissue derived from two or three germ layers. Duodenal teratomas are extremely rare and have been exclusively reported in neonates and children. This is the third case of a teratoma primarily arising in the duodenum and the first case that occurred in an adult.CASE SUMMARY A 31-year-old male presented with clinical partial gut obstruction(epigastric pain, nausea, and vomiting). The physical examination showed a palpable illdefined mass on the left side of the abdomen. The computed tomography scan revealed a multiseptated cystic tumor at the retroperitoneal area. First, he underwent gastrojejunostomy to relieve the symptoms and was referred to a tertiary-care hospital. The second operation revealed a 10-cm solid-cystic mass originating from the third part of the duodenum and adhering to the abdominal aorta and pancreas. Segmental duodenectomy was performed. The pathological diagnosis was a mature cystic teratoma. The patient was asymptomatic at 5 mo after the operation.CONCLUSION Duodenal teratomas are extremely rare but should be included in the differential diagnosis in patients who present with intestinal obstruction. Radiological imaging is helpful to reach the preoperative diagnosis. Multidisciplinary team planning is essential to avoid injury to the adjacent organ in duodenal operation.