Endocrine Abstracts

Succinate dehydrogenase (SDH) mitochondrial enzyme complex mutations are associated with hereditary paragangliomas and phaeochromocytomas. Of late, there has been more awareness of the development of other tumours in this patient cohort. There is limited evidence of propensity for development of Prolactinomas and other pituitary tumours in patients harbouring mutations in the SDH complex genes. We present three cases attending our center with a diagnosis of prolactinoma and SDH complex mutations.

Case 1: 61 year old gentleman, presented with a large right-sided carotid body tumour. Three years previously he had been diagnosed with a macroprolactinoma and continues to be managed on Cabergoline. Upon further review, the patient reported that his nephew had been diagnosed with two Phaeochromocytomas. There was no other family history. Genetic testing confirmed an SDHB mutation.

Case 2: 40 year old gentleman was found to have a macroprolactinoma. On extensive history taking he reported a strong family history of phaeochromocytoma. Consequently, he underwent genetic testing, resulting in a diagnoses of SDHB mutation. He was also found to have a large right lung mass, which was confirmed to be a carcinoid tumour following resection. His investigations pre-surgery identified mildly elevated metanephrines He underwent surgery after appropriate alpha and beta blockade and subsequently metanephrines normalised.

Case 3: A gentleman diagnosed with a macroprolactinoma in his early 20’s. His mother was noted to have a confirmed paraganglioma syndrome secondary to a mutation in SDHC gene. His genetic testing has confirmed the same genetic mutation. His investigations including metanephrines and radiological scans have proved normal, apart from a small (6 mm) lung nodule that is under surveillance.

Discussion: Our case series highlights the potential propensity for development of pituitary tumours in patients who have mutations in the SDH complex genes. This would inform the follow up that they currently receive to include pituitary imaging and biochemical profiling. In our patient cohort, macroprolactinoma was diagnosed prior to the development of phaochromocytoma or paragangliomas. Larger case series would be needed to confirm the association and the clinical course.