Abstract
Compared to other familial pheochromocytoma/paragangliomas (PHEO/PGLs), the succinate dehydrogenase subunit B (SDHB)-related PHEO/PGLs often present with aggressive and rapidly growing metastatic lesions. Currently, there is no proven effective treatment for malignant PHEO/PGLs. Here, we present a 35-year-old white man with primary malignant abdominal extra-adrenal 11 cm paraganglioma underwent surgical successful resection. But 6 months later, he developed extensive bone, liver, and lymph nodes metastasis, which were demonstrated by computed tomography scan and the (18)F-fluorodeoxyglucose positron emission tomography. However, his (123)I-metaiodobenzylguanidine scintigraphy was negative; therefore, the cyclophosphamide, vincristine, and dacarbazine (CVD) combination chemotherapy was initiated. The combination chemotherapy was very effective showing 80% overall reduction in the liver lesions and 75% overall reduction in the retroperitoneal mass and adenopathy, and normalization of plasma catecholamine and metanephrine levels. However, plasma levels of dopamine (DA) and methoxytyramine (MTY) were only partially affected and remained consistently elevated throughout the remaining period of follow-up evaluation. Genetic testing revealed an SDHB gene mutation. Here, we present an SDHB-related PHEO/PGL patient with extensive tumor burden, numerous organ lesions, and rapidly growing tumors, which responded extremely well to CVD therapy. We conclude patients with SDHB-related PHEO/PGLs can be particularly sensitive to CVD chemotherapy and may have an excellent outcome if this therapy is used and continued on periodic basis. The data in this patient also illustrate the importance of measuring plasma levels of DA and MTY to provide a more complete and accurate assessment of the biochemical response to therapy than provided by measurements restricted to other catecholamines and O-methylated metabolites.
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