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

Abstract

Prolactin (PRL)-secreting macroadenomas usually measure between 10 and 40mm. Giant (adenoma size ≥40mm) PRL-tumors are not common, and larger prolactinomas (maximal diameter ≥60mm) 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 ≥60mm; PRL>1000ng/ml) and summarized their characteristics and response to treatment. Mean age was 36.3±13.5years (range 12-59years). Mean adenoma size was 71.8±10.2mm (60-92mm). 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 28,465ng/ml (range 1300-270,000). All patients were treated with cabergoline (3.9±2.0mg/week), except for one who received bromocriptine. Treatment achieved PRL normalization in 11/18 patients within a median interval of 20months. 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±5.1years, 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. 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.