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

Objectives: Prolactin (PRL)-secreting macroadenomas usually measure between 10 and 40 mm. Giant (adenoma size ≥40 mm) PRL-tumors are not common, and larger prolactinomas (maximal diameter ≥60 mm) are rare, and their management outcomes have not been well characterized. Methods: We have identified 18 subjects (16 men, 2 females) with giant PRL-adenomas (size ≥60 mm; PRL > 1000 ng/ml) and summarized their characteristics and response to treatment. Results: 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 × ULN), and 4 remain with significantly elevated PRL. Most patients reported disappearance or improvement of their complaints. Conclusions: 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.