Metastatic duodenal germ cell tumor diagnosed with endoscopic ultrasound.

Testicular tumors are the most common solid tumors reported in young males aged 15–35 years [1, 2]. These tumors frequently metastasize to retroperitoneal lymph nodes, but only 5% of these tumors seed the gastrointestinal (GI) tract [3, 4], with the duodenum being the least common site (1.4%) [4]. Local extension from the retroperitoneal lymph node into the GI tract is the common method of spread. We report on a 44-year-old man with symptoms of gastric outlet obstruction. Computed tomography (CT) of the abdomen showed a bilobed retroperitoneal mass of 7×5 cm compressing the duodenum, suspicious for duplication cyst (▶Fig. 1a, b). Esophagogastroduodenoscopy showed a subepithelial nearobstructive mass in the second portion of the duodenum, which appeared cystic on palpation with closed forceps (▶Fig. 1 c). Endoscopic ultrasound (EUS) showed a 7×5.4 cm solid cystic mass (▶Fig. 1d). Fine-needle biopsy (FNB) with a 22-gauge needle (▶Fig. 1 e) revealed poorly differentiated epithelioid carcinoma, with unknown primary. Given the patient’s age, testicular tumor was a highly likely differential diagnosis. The patient underwent pancreas-sparing duodenal resection. Histology showed a mixed germ cell tumor with unusual presence of cartilage (▶Fig. 1 f). Ultrasound of the testes showed a 1.7 cm E-Videos