Intraperitoneal seeding of a testicular mixed germ cell tumor following spontaneous intraperitoneal mass rupture with associated anti-NMDA paraneoplastic encephalitis.

A 25-year-old male was admitted to the neurological intensive care unit for neurologic deterioration, likely caused by a paraneoplastic syndrome secondary to testicular malignancy. He experienced spontaneous rupture and hemorrhage of his testicular mass arising from an undescended testis while admitted. The tumor was excised, revealing a mixed germ cell tumor. Serum tumor markers began to rise after 4 cycles of chemotherapy. Surveillance scans 32 weeks after mass rupture revealed numerous tumor deposits throughout his peritoneum concerning for teratoma. We review a case of intraperitoneal metastasis of a testicular mixed germ cell tumor following intra-abdominal mass rupture.