SDHC Mutations are Associated with Cardiac Paragangliomas: A Case Report of a Patient With a Dopamine-Secreting Tumor and Review of the Literature

ABSTRACT Objective: Paragangliomas are rare tumors of neuroendocrine origin; approximately 30% of these tumors are related to an underlying genetic condition. Many of the hereditary paragangliomas, particularly those arising in the head and neck, have been linked to mutations in genes encoding different subunits of the succinate dehydrogenase (SDH) enzyme complex. The authors report an atypical presentation of a rare mutation in the SDH complex subunit C gene (SDHC). Methods: We reviewed the patient's clinical course, along with relevant literature for similar reported cases. Results: A 45-year-old woman with a background of multiple and recurrent paragangliomas (left glomus jugulare, right carotid body tumor, intrathyroidal and right lung paragangliomas) was found to have an intrapericardiac paraganglioma associated with excess levels of dopamine metabolites. Simultaneously, the proband's son was diagnosed with a macroprolactinoma at age 23 years. Genetic workup identified an underlying germline mutation in the gene encoding SDHC, consistent with the diagnosis of familial paraganglioma syndrome type 3. Current knowledge regarding the clinical implications of an SDHC gene mutation have been reviewed. Conclusion: Patients with SDHC gene mutations can develop paragangliomas within the pericardium. Our patient presented with multiple recurrent paragangliomas, in different locations, including within the pericardium. These tumors were functional, including a dopamine-secreting paraganglioma. The presence of multiple paragangliomas, the cardiac localization of tumors, the high risk of recurrence, and the elevation of 3-methoxytyramine levels should be taken into account when treating these patients. In addition, the diagnosis of macroprolactinoma in our patient's son reinforces the reported association between SDH mutations and the development of pituitary tumors. Abbreviations: MRI magnetic resonance imaging RET RET proto-oncogene SDH succinate dehydrogenase SDHB succinate dehydrogenase enzyme complex subunit B SDHC succinate dehydrogenase enzyme complex subunit C