Reversal of severe cognitive impairment following medical treatment of cystic invasive giant prolactinoma

Giant prolactinomas are rare tumours of the pituitary, which typically exceed 40 mm in their largest dimension. Impairment of higher cognitive function has been noted post-operatively after transcranial surgery and as a long-term consequence of the radiotherapy treatment. However, there has been little that is reported on such disturbances in relation to the tumour per se, and to our knowledge, there has been none in terms of responsivity to dopamine agonist therapy and shrinkage in these tumours. We present a case of successful restoration of severely impaired cognitive functions achieved safely after significant adenoma involution with medical treatment alone. LEARNING POINTS: Giant prolactinomas can be present with profound cognitive defects. Dopamine agonists remain in the mainstay first-line treatment of giant prolactinomas. Mechanisms of the reversible cognitive impairment associated with giant prolactinoma treatment appear to be complex and remain open to further studies. Young patients with giant prolactinomas mandate genetic testing towards familial predisposition.