Primary yolk sac tumor of the retroperitoneal region

Germ cell tumors (GCTs) are a group of tumors showing variations in clinical presentation and histopatho-logical and biological characteristics [1, 2]. The GCTs are neoplasms that develop from primordial germ cells of the human embryo, which are normally destined to produce sperm or ova. Primordial germ cells appear to originate in the yolk sac endoderm and migrate around the hind-gut to the genital ridge on the posterior abdominal wall where they become part of the developing gonad. Primary extragonadal germ cell tumors (EGCTs) are extremely rare and account for only a small percentage, 1% to 4%, of all germ cell tumors. Extragonadal yolk sac tumors (YSTs) are very rare. Typically they are found in the midline. The most common extragonadal sites are sacrococcygeal, mediasti-nal, intracranial, and retroperitoneal [2, 3]. Primary retroperitoneal EGCTs are rarely encountered neoplasms. Also, primary YST of the retroperitoneal region is an extremely rare neoplasm in childhood. Here, we report a primary retroperitoneal yolk sac tumor with liver metastases, treated with chemotherapy without surgery, in a 28-month-old boy. A 28-month-old boy presented with a week history of increasing abdominal swelling and abdominal pain. Physical examination showed an enlarged abdomen, and the liver edge was palpable 7–8 cm below the right costal margin. Hematological tests were normal. On biochemical analysis, AST and ALT were above two times the normal level, serum a-fetoprotein (AFP) was 80,000 ng/ml (normal is 0.6–7.9 ng/ml), lactate dehydrogenase was 578 IU/l (normal is 100–300 IU/l), and the human chorionic gonadotropin level was 0.5 mIU/ml (normal is 0–5 mIU/ ml). Serological studies were negative for viral hepatitis. Ultrasound revealed massive enlargement of the liver with multiple masses in both lobes. Contrast-enhanced magnetic resonance imaging (MRI) demonstrated that the liver was enlarged (17 cm diameter vertically) and had multiple solid lesions with a maximum size of 42 mm × 37 mm diameter, some of them having a lobular margin on T1-and T2-weighted images with decreased and high signal intensity, respectively. There was a heterogeneous contrast-enhanced solid lesion with diameter of 106 mm × 82 mm × 55 mm between the hilus of the liver and the left adrenal gland. In addition, the mass was surrounding the celiac and superior mesenteric arteries, and there was compression of the inferior vena cava and displacement of the pancreas anteriorly with an undistinguishable margin Fig. 1. Multiple solid lesions compatible with metastasis located from prevertebral area to liver hilus and …