A 3-year-old female rabbit (Oryctolagus cuniculi) presented with apathy and indisposition for 2–3 days. Palpation revealed a mass in the caudal abdomen, namely, in the wall of the uterus.
Ovariohysterectomy was performed, and the tissues were submitted for histopathologic examination.
The mass consisted of 3 different (trophoblastic, syncytiotrophoblastic, and cytotrophoblastic) neoplastic cell types originating from the uterus. Immunohistochemistry was positive for cytokeratin in all 3 neoplastic cell types, and the syncytiotrophoblasts were positive also for human chorionic
gonadotropin. Together these features allow the diagnosis choriocarcinoma. This report documents the first case of a spontaneous choriocarcinoma in a rabbit.