A 24-Year-Old Man Presenting with Lung Metastases from a Primary Retroperitoneal Extragonadal Choriocarcinoma

BACKGROUND Primary retroperitoneal choriocarcinoma is a rare form of extragonadal germ cell tumor that is highly aggressive and responds poorly to chemoradiation. Extragonadal choriocarcinomas are notoriously challenging to diagnose, and have often progressed to advanced disease by the time of diagnosis. The survival rate for extragonadal choriocarcinoma is approximately 30%, which is much lower than that of extragonadal non-seminomatous germ cell tumors (GCT) in general. CASE REPORT A 24-year-old man with no significant past medical history presented with left-sided, pleuritic chest pain and back pain radiating down his left leg, of 1-year duration. Computed tomography (CT) of the chest revealed multiple bilateral pulmonary nodules and a CT of the abdomen and pelvis showed a large heterogeneous soft tissue mass measuring 9.3×8×10.5 cm. A CT-guided core needle biopsy of a lung nodule was performed and the findings were consistent with the diagnosis of metastatic choriocarcinoma. Magnetic resonance imaging (MRI) of the brain was negative for metastatic disease. Tumor markers were significant for a markedly elevated beta human chorionic gonadotropin (B-hCG) of 104 712 mIU/mL. He was diagnosed with a stage IIIC germ cell tumor, further classified as a primary retroperitoneal choriocarcinoma with lung metastasis, and was started on urgent inpatient chemotherapy. CONCLUSIONS Due to the poor outcomes associated with extragonadal choriocarcinoma, it is important to promptly and correctly identify this malignancy in order to initiate treatment in a timely manner. The following case report explores the histopathologic characterization of this malignancy and describes the clinical course and outcomes from treatment for this patient.