Cystic Trophoblastic Tumor in a Primary Central Nervous System Post-Chemotherapy Germ Cell Tumor: The First Case Report.

Cystic trophoblastic tumor (CTT) is an uncommon trophoblastic proliferation of germ cell tumor origin, mostly reported in post-chemotherapy metastases of testicular germ cell tumors and rarely primary untreated testicular tumors. To date, we are not aware of occurrence in a non-testicular tumor. A 12-year-old boy presented with limb swelling, increased appetite, weight gain, and precocious puberty. Evaluation revealed right frontal lobe mass and elevated α-fetoprotein and β-human chorionic gonadotrophin. After response to neoadjuvant chemotherapy, the tumor was resected. Microscopically, the resection contained predominantly smooth muscle tissue with scattered small foci of glandular teratoma and CTT. Immunohistochemistry (SALL4, glypican 3) revealed no residual yolk sac tumor. Fluorescence in situ hybridization revealed gain of chromosome 12p. The patient has been disease-free for 13 years. This report expands the spectrum of primary central nervous system germ cell tumors with the occurrence of CTT in this site.