Metastatic Malignant Paraganglioma: A Case Report and Review of Literature.

Metastasis is a rare presentation of non-secretory paraganglioma. Consequently, there is no standard of care for the treatment of metastatic malignant paraganglioma. The most widely used chemotherapy regimen for non-resectable cases includes cyclophosphamide, vincristine, and dacarbazine (CVD). CVD has been previously studied with variable therapeutic response. However, yttrium-90 (Y90) radioembolization has not been previously studied in the treatment of hepatic metastasis in patients diagnosed with malignant paraganglioma. This case report follows the treatment of a patient with stage IV mediastinal paraganglioma with metastasis to the liver. Treatment consisted of the CVD chemotherapy regimen and Y90 radioembolization of the hepatic lesions. After 10 cycles of CVD, the tumor size has decreased from 6.0 × 8.8 to 5.5 × 3.0 × 3.4 cm on computed tomography scan. The prominent metastatic liver lesions responded after Y90 radioembolization of both the right and left hepatic arteries. The prominent right hepatic lobe lesion has decreased in size from 2.6 × 3.4 × 3.0 cm to 2.6 × 2.8 × 2.9 cm. The prominent left hepatic lobe lesion originally measuring 1.6 cm in diameter completely resolved on follow-up imaging studies. After completion of 12 cycles of chemotherapy, the most recent positron emission testing scan determined no evidence of disease regarding both the primary mass and the hepatic lesions. This study demonstrates the first case of combination chemotherapy and Y90 radioembolization with a complete response per response evaluation criteria in solid tumors criteria. The approaches toward diagnosis and treatment corresponding to this case of malignant metastatic paraganglioma are also reviewed in this study.