Endocrine Abstracts

Background: Paragangliomas are extremely rare endocrine tumours and can cause diagnostic difficulty, especially with a coexistent metastatic malignancy.

Case: A 78-year-old man with diagnosed metastatic melanoma underwent a PET scan for staging of the malignancy. It showed a left upper quadrant mass with multiple skeletal deposits and a lesion in the pituitary all with intense focal uptake. The mass was unusual for a metastatic lesion from melanoma although other lesions, including pituitary could be explained by metastatic melanoma. A biopsy of the abdominal mass showed histological features of a paraganglioma; 24-h urinary catecholamines showed raised noradrenaline 1474 nmol/24 h (70–550 nmol/24 h), dopamine 6277 nmol/24 h (400–3000 nmol/24 h) and a normal adrenaline <21 nmol/24 h (0–190 nmol/24 h) confirming a functional paraganglioma. The diagnosis of the skeletal lesions was unclear, and a 123-MIBG scan showed increased activity at the skeletal lesions but no avidity at pituitary confirming skeletal metastases from the paraganglioma with no definite explanation for the pituitary lesion. An MRI pituitary showed diffuse enlargement of pituitary gland with fossa expansion indicating chronicity and suggestive of prolactinoma rather than metastasis as his prolactin was 9400 mU/l and rest of his pituitary function was normal. He had no symptoms of diabetes insipidus. Resection of the paraganglioma was performed after preoperative alpha and beta blockade. His post-operative catecholamines normalised and post operative PET scan has shown stable appearance of skeletal lesions. He was started on Cabergoline for his prolactinoma and referred for chemotherapy for the metastatic skeletal lesions.

Conclusion: Metastatic paragangliomas in patients with a separate existing metastatic malignancy provides a diagnostic and management challenge. With a structured approach to investigation and management the clinical picture can be clarified, which then facilitates appropriate intervention.