Pheochromocytoma and paraganglioma: implications of germline mutation investigation for treatment, screening, and surveillance

High incidence of occult familial SDHD cases amongst Czech patients with head and neck paragangliomas

Introduction

Head and neck paragangliomas (HNPGLs) are rare neuroendocrine tumors, which are mostly benign in nature. Amongst all genes, Succinate Dehydrogenase Subunit D (SDHD) is the most commonly mutated in familial HNPGLs. In about 30% of HNPGLs, germline mutations in SDHD can also occur in the absence of positive family history, thus giving rise to "occult familial" cases. Our aim was to evaluate the pattern of SDHD germline mutations in Czech patients with HNPGLs.

Materials and methods

We analyzed a total of 105 patients with HNPGLs from the Otorhinolaryngology departments of 2 tertiary centers between 2006 - 2021. All underwent complex diagnostic work-up and were also consented for genetic analysis.

Results

Eighty patients aged 13-76 years were included; around 60% with multiple PGLs were males. Carotid body tumor was the most frequently diagnosed tumor. Germline SDHD mutation was found in only 12% of the Czech patients; approximately 78% of those harboring the mutation had negative family history. The mutation traits had higher affiliation for multiple tumors with nearly 70% patients of ≤ 40 years of age.

Conclusion

An SDHD mutation variant was shared amongst unrelated patients but no founder-effect was established. Our findings confirmed that the pattern of SDHD mutation distribution amongst HNPGLs in Czech Republic differs from most studies worldwide.

Familial SDHB gene mutation in disseminated non-hypoxia-related malignant paraganglioma treated with [90Y]Y/[177Lu]Lu- DOTATATE

Familial paraganglioma may be related to mutations in succinate dehydrogenase (SDH) enzyme complex genes. Among patients with hereditary paraganglioma, SDH subunit B (SDHB) gene mutations are associated with the highest morbidity and mortality related to a higher malignancy rate. We report a family with the c.689G>A (p.Arg230His) mutation in the SDHB gene identified in two family members, a father and his daughter. While the 14-year-old daughter had no evidence of clinical disease, recurrent and later disseminated [¹³¹I]metaiodobenzylguanidine uptake-negative head and neck paraganglioma with multiple bone metastases developed in the father who underwent peptide receptor radionuclide therapy with [⁹⁰Y]Y/[¹⁷⁷Lu]Lu-dodecane tetraacetic acid octreotate (DOTATATE) at the time of the genetic diagnosis. This treatment was repeated 6 years later due to disease progression and the patient, who is currently 49 years old, remains alive and in good overall clinical condition at 8 years of follow-up after the original presentation at our unit. The growing armamentarium of imaging methods available for such patients may inform decision making regarding choice of the optimal treatment approach, potentially contributing to improved outcomes.

Perioperative control of paroxysmal hypertension using esmolol with alpha-blockade in a child with a germline mutated paraganglioma

Summary

The use of antihypertensive medications in patients with pheochromocytomas and paragangliomas (PCC/PG) is usually a challenge. We report a case of familial paraganglioma that was successfully treated by esmolol and other antihypertensive medications without associated perioperative complications. Our patient was an 11-year-old girl who presented with classic symptoms and signs of PCC/PG and a CT scan of the abdomen that showed a right-sided paravertebral mass. Her father was diagnosed with paraganglioma a few years ago. Prazosin had been started but she continued to experience uncontrolled paroxysms of blood pressure (BP). She was known to have asthma; hence, she developed serious bronchospasm with atenolol. She was, therefore, switched to esmolol that successfully controlled her BP in addition to prazosin and intermittent doses of hydralazine prior to laparoscopic surgery with no side effects of medications or postoperative complications. Esmolol could be a good alternative to routinely used beta-blockers in children with PCC/PG with labile hypertension and related symptoms in the pre and intra-operative periods. It is titrable, effective, and can be weaned rapidly helping to avoid postoperative complications. Further larger studies on the use of esmolol in children with PCC/PG are needed to confirm our observation.

Learning points

In addition to alpha-blockers, esmolol could be a good alternative for routinely used beta-blockers to control paroxysmal hypertension and tachycardia in the pre- and intra-operative periods. Esmolol is titrable and an effective beta-blocker. It can be weaned rapidly helping to avoid postoperative complications in children with PCC/PG. Children with PCC/PG and other comorbidity like asthma may particularly benefit from the use of esmolol due to no or less side effects on airway resistance and the advantage of rapid titration of the medication compared to other beta-blockers.

SDHB-Associated Paraganglioma Syndrome in Africa-A Need for Greater Genetic Testing

A germline mutation is identified in almost 40% of pheochromocytoma/paraganglioma (PPGL) syndromes. Genetic testing and counseling are essential for the management of index cases as well as presymptomatic identification and preemptive management of affected family members. Mutations in the genes encoding the mitochondrial enzyme succinate dehydrogenase (SDH) are well described in patients with hereditary PPGL. Among patients of African ancestry, the prevalence, phenotype, germline mutation spectrum, and penetrance of SDH mutations is poorly characterized. We describe a multifocal paraganglioma in a young African male with an underlying missense succinate dehydrogenase subunit B (SDHB) mutation and a history of 3 first-degree relatives who died at young ages from suspected cardiovascular causes. The same SDHB mutation, Class V variant c.724C>A p.(Arg242Ser), was detected in one of his asymptomatic siblings. As there are limited data describing hereditary PPGL syndromes in Africa, this report of an SDHB-associated PPGL is a notable contribution to the literature in this growing field. Due to the noteworthy clinical implications of PPGL mutations, this work highlights the existing need for broader genetic screening among African patients with PPGL despite the limited healthcare resources available in this region.