Endocrine Abstracts

Germline mutations in the succinate dehydrogenase subunit-B gene (SDHB) are well recognised for predisposing to head and neck paraganglioma, sympathetic paraganglioma, phaeochromocytoma and renal cell carcinoma. The co-existence with pituitary adenomas remains uncommon.

We report a 31-year-old female who presented at age 29 years old with 9 months of secondary amenorrhoea. Prolactin was 3000 mIU/l and a 1.7-cm macroprolactinoma revealed on MR pituitary. Taking prolactin-lowering therapy, she achieved normal menses and subsequent MRI imaging demonstrated reduction in the size of this macroprolactinoma. At age 30 years, she was found to have a paraganglioma in the aortic–pelvic region. On reflection, she had noticed anxiety, sweating, palpitations and extreme exercise intolerance for the 2 years preceding diagnosis, which resolved following surgical resection. She was screened for familial paragangliomas, which revealed she was a carrier of the SDHB mutation. Interval screening MRI neck to pelvis has since demonstrated no evidence of recurrent or new disease. Plasma metanephrines have subsequently remained normal.

Her father, aged 64 years old, was referred for genetic counselling and testing. He too is an SDHB mutation carrier. His plasma metanephrines are normal and MRI neck to pelvis has not revealed a paraganglioma or phaeochromocytoma. Both the index case and father will remain under lifelong specialist care in a Neuroendocrine Tumours Clinic. Family members have been advised to seek genetic counselling.

Although uncommon, increasing incidence of pituitary adenomas in carriers of SDH mutations are being reported. These pituitary adenomas tend to be larger with macroprolactinomas commoner than other pituitary adenomas. Screening programmes vary widely for carriers of SDH mutations and tend not to involve pituitary imaging. However, given the association with pituitary lesions, screening imaging might need to include the pituitary. At present, however, it is thought that this is likely to be a low-yield strategy.