原発巣不明の転移性性腺外胚細胞腫瘍の猫の1例

抄録

A 9-year-old male cat, castrated at 10 months of age, was referred to this animal hospital due to an intra-abdominal mass. The mass was surgically resected and diagnosed as lymph node metastasis of an extragonadal germ cell tumor, based on histopathology and immunohistochemistry. No primary lesions were found intraoperatively or on CT images. The cat underwent 5 cycles of intravenous doxorubicin chemotherapy （1 mg/kg） administered at 3-week intervals. At 720 days after the initial examination, a new intra-abdominal mass was found on abdominal ultrasonography and removed surgically. Histopathology revealed similarities with the previous mass, leading to the diagnosis of a new metastatic lesion. Since complete resection margins were not achieved, the cat underwent 5 cycles of intravenous carboplatin chemotherapy （250 mg/m²） administered at 3-week intervals. At 1506 days after the initial examination, no evidence of neoplasms had been found and the cat maintained good health. This case highlights that feline extragonadal germ cell tumors can potentially invade the lymph nodes and form intraperitoneal metastases, and such cases can benefit from surgical resection.