Retroperitoneal germ cell tumor diagnosed by endoscopic ultrasound-guided fine needle aspiration

Figure 1 Computed tomography image revealing a large mass in the retroperitoneum abutting the pancreas and compressing the inferior vena cava.

Figure 2 Endoscopic ultrasound image of a well-circumscribed hypoechoic mass compressing the inferior vena cava and aorta.

Figure 3 Photomicrographs. A: A fine needle aspirate revealing undifferentiated anaplastic carcinoma of unclear origin (DiffQuik™ stain, × 400); B: A fine needle aspirate revealing a strong nuclear immunostaining pattern consistent with a germ cell tumor, favoring seminoma (OCT-4 stain - HE counterstain, × 200).