Cystic Trophoblastic Tumor

**Semantic type:** Neoplastic Process

**Definition:** A rare trophoblastic neoplasm that arises in metastatic sites of testicular mixed germ cell tumors following chemotherapy, or is part of treated or untreated testicular mixed germ cell tumors, or is secondary to either chemotherapy-induced or spontaneous regression of testicular choriocarcinoma. It has also been described in central nervous system post-chemotherapy primary germ cell tumors. It is characterized by the presence of cysts lined by squamoid trophoblastic cells. The cysts are often compressed surrounded by other germ cell components.

**Synonyms:** - CTT - Choriocarcinoma-Like Lesion