Succinate dehydrogenase subunit B (SDHB) mutations are associated with a high risk of developing pheochromocytomas, paragangliomas and renal cell tumours. The risk of malignancy is also higher than that of other SDH mutations.
A 23-year-old woman was referred to endocrine clinic following confirmation of an SDHB mutation. Her family was screened when a relative underwent a medical, prior to starting a new job, and a significant family history of renal tumours was discovered. The patients grandmother had two siblings with renal cancer and a further sibling with bone metastases of unknown origin. The patients uncle, mother and brother were found to have SDHB mutations. The uncle was discovered to have a renal tumour whereas the mother had normal imaging and biochemistry; the brother is currently under investigation.
The patient had no symptoms of a catecholamine-producing tumour, did not complain of back pain or abdominal pain and had normal urinary catecholamines. A routine screening CT scan of the abdomen, however, revealed a large, heretogeneously enhancing mass in the right para-aortic region, arising from the organ of Zuckerkandl. Pre-operative clinical examination confirmed the presence of an abdominal mass. Surgical resection of the mass was difficult as it was adherent to all surrounding tissue. The mass measured 10×6.3×11.2 cm and immunohistochemistry confirmed it to be a benign paraganglioma.
This case demonstrates the importance of genetic screening when considering SDH mutations. Due to non-penetrance, a three-generation family history is necessary as the relevant diseases may appear to skip a generation. This young woman had a very large tumour which was detected in the absence of symptoms and would not have been diagnosed if the physician conducting the medical had missed the strong family history of renal cancer. Early detection is especially important due to the malignant potential of these tumours.