Endocrine Abstracts

Introduction: Paraganglioma type 4 is the second most common hereditary paraganglioma syndrome. It is due to a mutation in the succinate dehydrogenase B (SDHB) gene. Associated with high morbimortality for presenting high penetrance (77%) and debut at an early age with a high probability of malignancy (31–71%). In terms of follow-up, annual biochemical monitoring is recommended for mutation carriers. However, the affected gene should be taken into account, for example: there is a high morbidity associated with undiagnosed paragangliomas in patients with SDHB mutations, which requires closer monitoring. In addition to biochemical testing, periodic imaging tests should be considered to detect biochemically silent tumors.

Clinical case: 62-year-old male, carrier of the c166-170del CCTCA mutation of the SDHB gene. Cardiac paraganglioma is detected by octreoscan in 2015. The left ventricular tumor is resected respecting left ventricle and coronary sine. The anatomic pathology findings are compatible with subepicardial paraganglioma that affects the resection margin. Regarding follow-up, during the first year it is quarterly, using methynephrine catecholamines and methoxytyramine (negative); and with a semi-annual imaging test where a small recurrence adjacent to the coronary sinus is detected in MRI, with uptake in PET/CT, therefore ruling out cardiac surgery. During the second and third year, semi-annual follow-up with catecholamines and methanephrines (negative) and imaging tests using PET/CT (radiological stability). During the fourth year, semi-annual follow-up by methoxytyramine, catecholamines and methanephrines (negative), and annual imaging tests, with octreoscan (negative) and PET/CT (lack of progression), and findings of a focal increase of metabolism in the right colon that turns out to be a false positive.

Conclusion: Cardiac paragangliomas are exceptional, making up 1% of all cardiac tumors. The most aggressive variant of SDH mutations is SDHB, presenting a 77% penetrance and a malignancy risk of up to 71%. Genetic study of the relatives of an affected individual is essential for an early diagnosis. Monitoring is performed by biochemical determinations of catecholamines and methanephrines and imaging tests (MRI, PET/CT), with a variable periodicity depending on the morbidity associated with the genetic mutation.