Endocrine Abstracts

Case Report: A 42 year-old male, with a family history of phaeochromocytomas and paragangliomas, was diagnosed as a carrier of the succinate dehydrogenase subunit-B (SDHB) mutation. He was also diagnosed with macroprolactinoma and treated with cabergoline (currently 250 mcg weekly). A contrast CT chest scan, performed as part of the surveillance program for SDHB-associated tumours, revealed a small right lung lesion, which was found to be OctreoScan^TM positive. The patient was asymptomatic and previously smoked ten cigarettes daily. Urinary and plasma metanephrines were normal. He underwent a right VATS (video-assisted thoracoscopic surgery) sublobar wedge resection. Two typical carcinoids (TCs) were found (according to the WHO 2015 classification) measuring 7 and 6 mm in diameter. TNM was pT1a (2) Nx L0 V0 PL0 Rx. The cellular marker of proliferation, Ki-67, was 1 and 5% respectively. Immunohistochemical analysis showed that the neoplastic cells expressed neuroendocrine markers including chromogranin A and synaptophysin. At 1 year follow-up CT scan, a new 34 mm octreotide-avid mass was found at the site of the original resection. The multidiscliplinary team referred the patient for a right lobectomy. The pathology report indicated another TC: pT1b (25 mm) N0 Mx PL0 R0, Ki-67 4%. Biochemical markers including plasma chromogranin A and metanephrines remained within the normal range. The follow-up plan was a FDG-PET CT scan after 6 months in order to early detect a possible lung carcinoid recurrence or the presence of phaeochromocytomas/paragangliomas.

Discussion and Conclusions: Germline mutation of SDHB predispose to head-and-neck-paraganglioma, sympathetic paraganglioma, phaeochromocytoma and renal cell carcinoma. Recently it has been suggested that germline SDH mutations can rarely be associated with pituitary adenomas, most frequently macroprolactinomas. To our knowledge, this case represents the tenth patient with an SDHB-associated pituitary adenoma.

TCs occur in the fourth to sixth decades of life and tend to grow very slowly. The majority are sporadic, though somatic MEN1 (multiple endocrine neoplasia type 1) gene mutations have been reported.

This is the first case of an SDHB-associated TC. Interestingly, the TCs showed aggressive behaviour. Given the rarity of both diseases, the possibility of a new phenotype-genotype correlation should be considered.