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Summary
At least 40% of phaeochromocytomas and paraganglioma’s (PPGLs) are associated with an underlying genetic mutation. The understanding of the genetic landscape of these tumours has rapidly evolved, with 18 associated genes now identified. Among these, mutations in the subunits of succinate dehydrogenase complex (SDH) are the most common, causing around half of familial PPGL cases. Occurrence of PPGLs in carriers of SDHB, SDHC and SDHD subunit mutations has been long reported, but it is only recently that variants in the SDHA subunit have been linked to PPGL formation. Previously documented cases have, to our knowledge, only been found in isolated cases where pathogenic SDHA variants were identified retrospectively. We report the case of an asymptomatic suspected carotid body tumour found during surveillance screening in a 72-year-old female who is a known carrier of a germline SDHA pathogenic variant. To our knowledge, this is the first screen that detected PPGL found in a previously identified SDHA pathogenic variant carrier, during surveillance imaging. This finding supports the use of cascade genetic testing and surveillance screening in all carriers of a pathogenic SDHA variant.
Learning points:
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SDH mutations are important causes of PPGL disease.
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SDHA is much rarer compared to SDHB and SDHD mutations.
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Pathogenicity and penetrance are yet to be fully determined in cases of SDHA-related PPGL.
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Surveillance screening should be used for SDHA PPGL cases to identify recurrence, metastasis or metachronous disease.
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Surveillance screening for SDH-related disease should be performed in identified carriers of a pathogenic SDHA variant.
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Summary
A 48-year-old hypertensive and diabetic patient presented with a 10-year history of progressive right facial pain, tinnitus, hearing loss, sweating, and palpitations. Investigations revealed a 5.6 cm vascular tumor at the carotid bifurcation. Her blood pressure (BP) was 170/110, on lisinopril 20 mg od and amlodipine 10 mg od and 100 U of insulin daily. A catecholamine-secreting carotid body paraganglioma (CSCBP) was suspected; the diagnosis was confirmed biochemically by determining plasma norepinephrine (NE) level, 89 000 pmol/l, and chromogranin A (CgA) level, 279 μg/l. Meta-iodobenzylguanidine and octreotide scanning confirmed a single tumor in the neck. A week after giving the patient a trial of octreotide 100 μg 8 h, the NE level dropped progressively from 50 000 to 25 000 pmol/l and CgA from 279 to 25 μg/l. Treatment was therefore continued with labetalol 200 mg twice daily (bid) and long-acting octreotide-LA initially using 40 mg/month and later increasing to 80 mg/month. On this dose and with a reduced labetalol intake of 100 mg bid, BP was maintained at 130/70 and her symptoms resolved completely. CgA levels returned to normal in the first week and these were maintained throughout the 3 month treatment period. During tumor resection, there were minimal BP fluctuations during the 10 h procedure. We conclude that short-term high-dose octreotide-LA might prove valuable in the preoperative management of catecholamine-secreting tumors. To the best of our knowledge, this is the first report on the successful use of octreotide in a CSCBP.
Learning points
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The value of octreotide scanning in the localization of extra-adrenal pheochromocytoma.
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Control of catecholamine secretion using high-dose octreotide.
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This is a report of a rare cause of secondary diabetes and hypertension.
