The growing teratoma syndrome after subtotal resection of an intracranial nongerminomatous germ cell tumor in an adult: case report.

Objective and Importance: We report a rare complication after resection of a recurrent intracranial nongerminomatous germ cell tumor in an adult. The growing teratoma syndrome, as originally described with pediatric germ cell neoplasms, represents tumor recurrence, often cystic, that sometimes is observed after partial response to multimodality therapy and despite decreasing tumor serum markers. The enlarging tumor consists of elements of a mature teratoma that presumably are refractory to chemotherapy or radiation. To our knowledge, this is only the third case of the growing teratoma syndrome in an adult patient with nongerminomatous germ cell tumor.
Clinical Presentation: A 26-year-old man had signs of recurrent obstructive hydrocephalus 6 months after multimodality treatment of a diencephalic yolk sac tumor and endoscopic third ventriculostomy. Imaging studies revealed large multilocular cystic masses originating from the tumor bed and partially obstructing the ventriculostomy.
Intervention: Near total tumor resection and fenestration was performed. Histopathological analysis demonstrated a mature teratoma.
Conclusion: Surgical resection, if feasible, is the treatment of choice for the growing teratoma syndrome to establish the correct diagnosis and prevent complications.