Retroperitoneal extragonadal germ cell tumor with duodenal infiltration: A challenging endo‐luminal tissue diagnosis

A 32‐year‐old Malay male was referred to our hospital for a second opinion. An abdominal and pelvic CT scan at the previous medical facility showed a large retroperitoneal tumor, which was subjected to ultrasound‐guided fine‐needle aspiration cytology (FNAC) with a provisional diagnosis of malignant lymphoma. However, after reviewing the existing results, a repeat biopsy was deemed necessary and this was performed endoluminally via gastroduodenoscopy in view of the close proximity of the tumor and the third part of the duodenum. The first biopsy failed to detect any abnormal cells, but a repeat biopsy with supporting evidence from other laboratory results led to a final diagnosis of extragonadal germ cell tumor (GCT) with duodenal infiltration.