Atypical Giant Suprasellar Prolactinoma Presenting With Visual Field Changes in the Absence of Symptoms of Hyperprolactinemia

Prolactinomas are benign tumors that make up the majority of all pituitary adenoma cases and present most commonly in women. Prolactinomas presenting in adolescents and children, however, are extremely rare. We report a case of a 17-year-old male who presented with a six-month history of headaches and a previously unrecognized visual field deficit on examination. Neuroimaging revealed a large suprasellar tumor with imaging, more characteristic of a craniopharyngioma or suprasellar low-grade glioma impinging, on the left intracranial optic nerve causing right-sided hemianopsia. Due to the extensive mass effect and bitemporal hemianopsia on examination, the decision to proceed with initial surgical debulking was made following informed consent. A subtotal resection was performed where the pathology was consistent with a prolactinoma that correlated with markedly elevated prolactin (PRL) levels obtained pre and post-operatively that have not resulted until five days post procedure. The patient was subsequently treated with dopamine agonist (DA) cabergoline therapy and is now five-years disease-free with normal neurological examination and no residual tumor on neuroimaging. DA therapy has shown high clinical efficacy and should be considered prior to any surgical intervention; however, extensive mass effect may appropriate surgical debulking to increase therapy efficacy. Our case highlights an atypical appearance of a giant prolactinoma that may mimic other more common suprasellar tumors, a presentation associated with unrecognized visual field deficits, and the importance of rapid turnaround testing for serum PRL that may aid in the upfront diagnosis and management of prolactinomas.