Endocrine Abstracts

Background: Prolactinomas are usually highly sensitive to dopamine agonists. We report the use of temozolomide in a 47-year-old gentleman with MEN 1 and a highly dopamine agonist-resistant, and aggressive prolactinoma.

Case summary: He presented in 2001 with a 3rd nerve palsy and recurrent headaches. MRI revealed a pituitary tumour extending into the left cavernous sinus. Prolactin levels were 29 000 mU/l. (NR<360). Primary hyperparathyroidism, a lesion in the head of the pancreas, and genetic analysis confirmed MEN 1. Treatment with cabergoline resulted in a rapid decrease in serum prolactin levels to 11 000 mU/l and resolution of the 3rd nerve palsy. After 12 months of therapy serum prolactin increased to 40 000 mU/l despite doses of cabergoline of 1 mg/day and symptoms reappeared. He underwent transsphenoidal surgery. Histology revealed strong prolactin immunoreactivity and an increased proliferative rate. After an initial fall, serum prolactin levels rose to 70 000 mU/l, tumour volume increased, and he underwent 3-field fractionated radiotherapy, resulting in a dramatic fall in prolactin within 6 months to 655 mU/l. Two years later further tumour expansion and increased prolactin (14 000 mU/l) was treated with stereotactic gamma knife radiosurgery, with a fall in prolactin to 800 mU/l at 4 months. In 2006, further tumour expansion and elevation in prolactin was treated with platinum-based chemotherapy, but this was ineffective. He developed a complete 3rd nerve palsy and the oral alkylating agent temozolomide was given. After 7 months prolactin levels dramatically improved from 24 000 to 800 mU/l, his neurodisabilities resolved and the tumour reduced in size, and continues to be controlled.

Conclusion: Prolactinomas in patients suffering from MEN 1 may behave more aggressively than their sporadic counterparts. This is the first reported case of an aggressive prolactinoma in a patient with MEN1, which has responded to temozolomide with clinical, biochemical and radiological improvement.