Giant prolactinomas larger than 60 mm in size: a cohort of massive and aggressive prolactin-secreting pituitary adenomas

Prolactin (PRL)-secreting macroadenomas usually measure between 10 and 40 mm. Giant (adenoma size a parts per thousand yen40 mm) PRL-tumors are not common, and larger prolactinomas (maximal diameter a parts per thousand yen60 mm) are rare, and their management outcomes have not been well characterized. We have identified 18 subjects (16 men, 2 females) with giant PRL-adenomas (size a parts per thousand yen60 mm; PRL > 1000 ng/ml) and summarized their characteristics and response to treatment. Mean age was 36.3 +/- 13.5 years (range 12-59 years). Mean adenoma size was 71.8 +/- 10.2 mm (60-92 mm). Complaints at presentation included headaches in 11 patients, visual deterioration in 9, sexual dysfunction in 9 males, and behavioral changes in two. Fourteen (78 %) had visual field defects. Mean PRL at presentation was 28,465 ng/ml (range 1300-270,000). All patients were treated with cabergoline (3.9 +/- 2.0 mg/week), except for one who received bromocriptine. Treatment achieved PRL normalization in 11/18 patients within a median interval of 20 months. Visual improvement occurred in 12/14 patients with pre-treatment visual abnormalities. Nine patients underwent surgery (transsphenoidal, 7; transcranial, 2). None of the seven patients with elevated PRL before surgery achieved remission post-operatively. After a follow-up of 7.8 +/- 5.1 years, 15/18 patients had significant adenoma shrinkage. Eleven patients are normoprolactinemic, 3 are partially controlled (PRL < 3 x ULN), and 4 remain with significantly elevated PRL. Most patients reported disappearance or improvement of their complaints. These enormous PRL-adenomas are invasive but respond fairly well to medical treatment. Long-term therapy with high dose cabergoline together with a pituitary surgery in some patients was the key for their successful management, achieving biochemical and clinical remission in most patients.