Abstract：
Tumor-to-tumor metastasis is a rare phenomenon in which primary tumor cells metastasize to other tumors. Herein, we report an extremely rare case of tumor-to-tumor metastasis of medullary thyroid carcinoma to a paraganglioma in a patient with multiple endocrine neoplasia type 2B. Based on genetic examination, a 36-year-old woman was diagnosed with multiple endocrine neoplasia type 2B when she was 24 years old. She had a history of total thyroidectomy for medullary thyroid carcinoma and bilateral adrenalectomy for pheochromocytomas, which were performed when she was 15 years and 29 years old, respectively. Follow-up computed tomography demonstrated a retroperitoneal tumor of 30 mm in diameter beside the left kidney and a liver tumor of 16 mm in diameter located in segment 6. The retroperitoneal and liver tumors were surgically resected and examined by a pathologist. Histological examination revealed the classic Zellballen pattern in the retroperitoneal tumor, rendering the diagnosis of a paraganglioma recurrence. Inside the tumor, a white nodule positive for carcinoembryonic antigen, weakly positive for calcitonin, and negative for tyrosine hydroxylase, was identified and diagnosed as a metastatic medullary thyroid carcinoma with high malignant potential. The liver lesion was diagnosed as a metastasis of the medullary thyroid carcinoma. This is the first report of tumor-to-tumor metastasis of medullary thyroid carcinoma to paraganglioma in a patient with multiple endocrine neoplasia type 2B twenty years after total thyroidectomy.
摘要：
肿瘤到肿瘤转移是一种罕见的现象，其中原发性肿瘤细胞转移到其他肿瘤。在这里，我们报道了1例2B型多发性内分泌瘤形成患者中甲状腺髓样癌向副神经节瘤转移的极其罕见病例.根据基因检查,一名36岁女性在24岁时被诊断为多发性内分泌瘤2B型.她有甲状腺髓样癌的甲状腺全切除术和嗜铬细胞瘤的双侧肾上腺切除术的病史，这是在她15岁和29岁的时候进行的，分别。随访计算机断层扫描显示，在左肾旁边有直径为30mm的腹膜后肿瘤，在第6段有直径为16mm的肝肿瘤。腹膜后和肝肿瘤经手术切除并由病理学家检查。组织学检查显示腹膜后肿瘤的经典Zellballen模式，提供副神经节瘤复发的诊断。在肿瘤内部，癌胚抗原呈阳性的白色结节,降钙素呈弱阳性，酪氨酸羟化酶阴性，被鉴定并诊断为具有高恶性潜能的转移性甲状腺髓样癌。肝脏病变被诊断为甲状腺髓样癌的转移。这是甲状腺全切除术20年后多发性内分泌瘤2B型患者甲状腺髓样癌向副神经节瘤的肿瘤转移的首次报道。
