Endocrine Abstracts

Giant prolactinomas are uncommon, with some individual case reports described in the literature, but with few series documenting treatment outcomes. They represent a therapeutic challenge, since restoring normoprolactinemia, eugonadism and reducing tumour size may not be realistic goals. Specific complications may also arise during treatment that change the initial management plans. The authors describe a case of a 28-year-old male with visual impairment and behavioural changes. The diagnosis of a macroprolactinoma was made, characterized by a lesion with 76 mm of larger diameter, supraselar extension, large anterior-superior cystic component and posterior-inferior solid component in relation with vascular and neural structures of the skull base. The endocrine study revealed prolactin levels of 158 700 uUi/ml (58–254), without associated hypopituitarism. A craniotomy was performed, but relapse of the cystic component in the first year of follow-up led to reintervention. Histologically the tumour was densely granulated, with strong diffuse immunostaining for prolactin, Ki-67 labelling index of 7% and p53 immunoreactivity of 42%. Bromocriptine was prescribed in a maximum daily dose of 45 mg, and a 92% reduction in prolactin levels was attained. Despite reduction in the cystic component, there were no significant changes in the solid component after treatment. Particular therapeutic questions arise. First, restoring eugonadism and normoprolactinemia is not feasible and the involvement of critical neural structures represents the major concern, but surgical approach of the solid component is difficult. High doses of bromocriptine or cabergoline may be associated with long term side effects. There is still the possibility of radiotherapy, with its known consequences. Second, this clinical course and the high Ki-67 labelling index associated with p53 staining alert to the possibility of a tumour with aggressive behaviour and malignant potential.