Hereditary pheochromocytoma/paraganglioma syndrome with a novel mutation in the succinate dehydrogenase subunit B gene in a Japanese family: two case reports

Background Pheochromocytoma and paraganglioma caused by succinate dehydrogenase gene mutations is called hereditary pheochromocytoma/paraganglioma syndrome. In particular, succinate dehydrogenase subunit B mutations are important because they are strongly associated with the malignant behavior of pheochromocytoma and paraganglioma . This is a case report of a family of hereditary pheochromocytoma/paraganglioma syndrome carrying a novel mutation in succinate dehydrogenase subunit B. Case presentation A 19-year-old Japanese woman, whose father died of metastatic paraganglioma, was diagnosed with abdominal paraganglioma, and underwent total resection. Succinate dehydrogenase subunit B genetic testing detected a splice-site mutation, c.424-2delA, in her germline and paraganglioma tissue. Afterwards, the same succinate dehydrogenase subunit B mutation was detected in her father’s paraganglioma tissues. In silico analysis predicted the mutation as “disease causing.” She is under close follow-up, and no recurrence or metastasis has been observed for 4 years since surgery. Conclusions We detected a novel succinate dehydrogenase subunit B mutation, c.424-2delA, in a Japanese family afflicted with hereditary pheochromocytoma/paraganglioma syndrome and found the mutation to be responsible for hereditary pheochromocytoma/paraganglioma syndrome. This case emphasizes the importance of performing genetic testing for patients with pheochromocytoma and paraganglioma suspected of harboring the succinate dehydrogenase subunit B mutation (that is, metastatic, extra-adrenal, multiple, early onset, and family history of pheochromocytoma and paraganglioma) and offer surveillance screening to mutation carriers.

SDHB Suppresses the Tumorigenesis and Development of ccRCC by Inhibiting Glycolysis

Metabolic reprogramming is the prominent feature of clear cell renal cell carcinoma (ccRCC). Succinate dehydrogenase subunit B (SDHB) is one of subunits of mitochondrial respiratory chain complex II. The loss of SDHB function is closely related with metabolic changes in kidney cancer cells. However, the role and molecular mechanism of SDHB in ccRCC occurrence and progression are still unclear. In this study, the results of bioinformatics analyses on GEO, TCGA and oncomine databases and immunohistochemistry showed that the expression level of SDHB was downregulated in ccRCC tissues. SDHB level was gradually downregulated as ccRCC stage and grade progressed. The low level of SDHB was associated with poor prognosis of ccRCC patients, especially for advanced ccRCC patients. Increased methylation levels in SDHB gene promoter led to the downregulation of SDHB level in ccRCC tissues. SDHB was correlated with many metabolism related genes and its interacting proteins were enriched in metabolic pathways. SDHB overexpression suppressed the proliferation, colony formation and migration of ccRCC cells by inhibiting aerobic glycolysis. SDHB may be a potential prognostic marker and therapeutic target for ccRCC.

Transaminitis Evaluation Leads to the Incidental Diagnosis of Familial Paraganglioma Due to SDHB Mutation

Background: Paragangliomas are rare neuroendocrine tumors. Patients with succinate dehydrogenase subunit B (SDHB) gene mutations are predisposed to developing paraganglioma/pheochromocytoma. We are presenting the case of an incidental finding of a paraganglioma during an evaluation for transaminitis. Clinical Case: A 23-year-old male with a medical history of right hydrocele repair as a teenager was evaluated with an ultrasound of the abdomen for elevated liver enzymes and right upper quadrant discomfort. The ultrasound revealed a large lobular solid vascular 13.8 x 8.1 x 11.3 cm mass in the mid abdomen. He underwent a CT of the chest, abdomen and pelvis which demonstrated a large retroperitoneal mass measuring 16 x 10 x 13.7 cm within the right mid abdomen. The mass was described as a large centrally necrotic peripherally enhancing right retroperitoneal mass displacing the IVC anteriorly. The patient subsequently underwent an image-guided biopsy of the mass and the pathology revealed it was a paraganglioma. The patient denied any history of hypertension, orthostasis, headaches or palpitations. Biochemical workup for plasma catecholamines, plasma metanephrines, 24-hour urine catecholamines and metanephrines and cortisol were unremarkable. His transaminitis also resolved. He underwent a retroperitoneal paraganglioma excision and the final pathology was consistent with paraganglioma and negative for capsular invasion. He was referred to a genetic counsellor for testing since paragangliomas can be inherited. He also mentioned a family history of breast cancer in his mother and HTN and prostate cancer in his father. His test revealed that he had a c.289A>T mutation in his SDHB gene. He was encouraged to share the information with his family to help them understand the implications of his genetic test result. He underwent a surveillance PET scan which showed multiple osseous lesions in his temporal calvarium, sphenoid, spine and sacrum suggestive of metastasis. Repeat imaging with a DOTATATE PET scan showed stable disease. His transaminitis was transient, and we did not find a correlation to his paraganglioma. His imaging tests showed no liver metastasis. A CT of the head showed no evidence of intracranial metastasis. The current plan is to continue surveillance. His older brother underwent a genetic testing. He tested positive for the same SDHB mutation and underwent biochemical and imaging tests which were unremarkable. He too will continue surveillance. Conclusions: Patients with a succinate dehydrogenase subunit B (SDHB) gene mutations are predisposed to developing paraganglioma/pheochromocytoma. The tumors produce catecholamines, but can be biochemically silent as in our patient. They are inherited in an autosomal dominant manner. Our case highlights the importance for genetic counseling which increases the chances of early screening and surveillance in affected family members for optimal multidisciplinary management of patients.

Urinary bladder paraganglioma metastatic to the lung in a patient with SDHB gene mutation: A case report

Introduction: Paragangliomas are tumors originating from the neural crest. Most of them are benign and arise from various locations in the body. Extra-adrenal paragangliomas arise as sporadic cases in most settings or as part of heredofamilial syndromes in about one-quarter of cases. Succinate dehydrogenase subunit B (SDHB) gene mutations are associated with an aggressive clinical disease course of pheochromocytoma/paraganglioma.Methods: We present a 41-year-old male former smoker with a history of a growing right upper lung nodule on chest imaging. He had no cough or respiratory symptoms. Twenty-seven months prior, the patient underwent a cystoprostatectomy due to paraganglioma of the bladder. Genetic testing identified a pathogenic mutation in SDHB gene, c.166_170delCCTCA (p.Pro56Tyrfs*5). He underwent a wedge resection of the lung nodule.Results: Sectioning of the lung wedge revealed a well-circumscribed, firm tan nodule. Microscopically there were nests of large neoplastic cells with round nuclei and eosinophilic granular cytoplasm. Tumor cells were positive for synaptophysin and chromogranin and negative for pan-cytokeratin. S-100 protein highlighted sustentacular cells. Morphologically, the pulmonary neoplasm was similar to the primary tumor of the bladder. These features are consistent with a bladder paraganglioma metastatic to the lung, in a background of a hereditary paraganglioma syndrome.Conclusion: Extra-adrenal paraganglioma occurring in a setting of hereditary paraganglioma syndrome has a high risk of metastasis. Lifelong surveillance even after prompt resection of the primary tumor with negative margins is required to ensure early detection of metastasis and prevent complications associated with it.

Somatostatin Receptors and Analogs in Pheochromocytoma and Paraganglioma: Old Players in a New Precision Medicine World

Neuroendocrine tumors overexpress somatostatin receptors, which serve as important and unique therapeutic targets for well-differentiated advanced disease. This overexpression is a well-established finding in gastroenteropancreatic neuroendocrine tumors which has guided new medical therapies in the administration of somatostatin analogs, both “cold”, particularly octreotide and lanreotide, and “hot” analogs, chelated to radiolabeled isotopes. The binding of these analogs to somatostatin receptors effectively suppresses excess hormone secretion and tumor cell proliferation, leading to stabilization, and in some cases, tumor shrinkage. Radioisotope-labeled somatostatin analogs are utilized for both tumor localization and peptide radionuclide therapy, with 68Ga-DOTATATE and 177Lu-DOTATATE respectively. Benign and malignant pheochromocytomas and paragangliomas also overexpress somatostatin receptors, irrespective of embryological origin. The pattern of somatostatin receptor overexpression is more prominent in succinate dehydrogenase subunit B gene mutation, which is more aggressive than other subgroups of this disease. While the Food and Drug Administration has approved the use of 68Ga-DOTATATE as a radiopharmaceutical for somatostatin receptor imaging, the use of its radiotherapeutic counterpart still needs approval beyond gastroenteropancreatic neuroendocrine tumors. Thus, patients with pheochromocytoma and paraganglioma, especially those with inoperable or metastatic diseases, depend on the clinical trials of somatostatin analogs. The review summarizes the advances in the utilization of somatostatin receptor for diagnostic and therapeutic approaches in the neuroendocrine tumor subset of pheochromocytoma and paraganglioma; we hope to provide a positive perspective in using these receptors as targets for treatment in this rare condition.

Paraganglioma of the Urinary Bladder Metastatic to the Lung in a Patient with SDHB Gene Mutation: A Case Report

Introduction/Objective Paragangliomas are tumors originating from the neural crest. Most tumors are benign and arise from various locations in the body. Extra-adrenal paragangliomas arise as sporadic cases in most settings or as part of heredofamilial syndromes in about one-quarter of cases. Succinate dehydrogenase subunit B (SDHB) gene mutations are associated with an aggressive clinical disease course of pheochromocytoma/paraganglioma. Methods We present a 41-year-old male former smoker with a history of a growing right upper lung nodule on chest imaging. He had no cough or respiratory symptoms. Twenty-seven months prior the patient underwent a cystoprostatectomy due to paraganglioma of the bladder. Genetic testing identified a pathogenic mutation in SDHB gene, c.166_170delCCTCA (p.Pro56Tyrfs*5). He underwent a wedge resection of the lung nodule. Results Sectioning of the lung wedge revealed a well circumscribed, firm tan nodule. Microscopically there were nests of large neoplastic cells with round nuclei and eosinophilic granular cytoplasm. Tumor cells were positive for synaptophysin and chromogranin and negative for pan-cytokeratin. S100 highlighted sustentacular cells. The pulmonary neoplasm was morphologically similar to the prior tumor of the bladder. These features are consistent with a metastatic urothelial paraganglioma to the lung, in a background of a hereditary paraganglioma syndrome. Conclusion Extra-adrenal paraganglioma occurring in a setting of hereditary paraganglioma syndrome has a higher risk of metastasis. Lifelong surveillance even after prompt resection of primary tumor with negative margins is required to ensure early detection of metastasis and prevention of complications associated with it.

MON-199 Targeting Pheochromocytoma/Paraganglioma with Polyamine Inhibitors

Background: Pheochromocytomas (PCCs) and paragangliomas (PGLs) are neuroendocrine tumors that are mostly benign. Metastatic disease occurs in about 10% of cases, and for these patients no effective therapies are available. Patients with mutations in the succinate dehydrogenase subunit B (SDHB) gene tend to have metastatic disease with very little treatment options. To find a new treatment strategy, we utilized a metabolomics approach to identify unique metabolic pathways. A metabolomic analysis was performed on human hPheo1 cells and shRNA SDHB knockdown hPheo1 (hPheo1 SDHB KD) cells. Additional analysis of 50 human fresh frozen PCC/PGL samples was conducted. Since the polyamine pathway surfaced in the metabolomics analysis, we hypothesized that treatment with polyamine inhibitors would be an effective option for aggressive PCC/PGL tumors. In vitro studies using N1,N11-diethylnorspermine (DENSPM) and N1,N12- diethylspermine (DESPM) treatments were carried out. DENSPM efficacy was assessed in xenograft models. Results: Components of the polyamine pathway were elevated in hPheo1 SDHB KD cells compared to wild-type cells. A similar observation was noted in SDHx PCC/PGLs tumor tissues compared to their SDHB wild-type counterparts. Specifically, spermidine, and spermine were significantly elevated in SDHx-mutated PCC/PGLs, with a similar trend in hPheo1 SDHB KD cells. Polyamine pathway inhibitors DENSPM and DESPM effectively inhibited growth of hPheo1 cells in vitro as well in mouse xenografts. Conclusions: This study demonstrates overactive polyamine pathway in PCC/PGL with SDHB mutations. Treatment with polyamine inhibitors significantly inhibited hPheo1 cell growth and led to growth inhibition in xenograft mouse models treated with DENSPM. These studies strongly implicate the polyamine pathway in PCC/PGL pathophysiology and provide new foundation for exploring the role for polyamine analogue inhibitors in treating metastatic PCC/PGL.