ODP334 Must we Wait for the Development of Metastasis to be Able to Distinguish Dopamine Resistant Aggressive Prolactinoma from Prolactin Producing Pituitary Carcinomas? Case Report and Literature Review

Abstract

Abstract Background Prolactinomas, the most prevalent type of neuroendocrine disease, account for approximately 40% of all pituitary adenomas. In the vast majority of cases, these are benign tumors with excellent clinical response to medical therapy with dopamine agonist agents such as bromocriptine and cabergoline. Rarely medical treatment fails to normalize prolactin levels and/or decrease the size of the tumor, posing a challenge to the clinician. Case presentation 40-year-old man who underwent resection of a 7.4 cm pituitary prolactinoma via frontal craniotomy followed by radiotherapy. He developed panhypopituitarism and was placed on chronic hormonal replacement therapy plus high dose cabergoline. Two years later he presented with recurrence of his disease and was diagnosed with an unresectable 4.9 cm pituitary adenoma showing cortical breakthrough of the sellar floor, invasion into the optic chiasm, erosion of the posterior sphenoid walls, extension into the sphenoid sinuses and posteriorly into the pons, midbrain and third ventricle, as well as complete encasement of the distal, superior cerebellar and posterior cerebral arteries. The patient underwent endoscopic trans sphenoidal partial tumor resection and CSF leak repair. Pathology revealed a pituitary prolactinoma with Ki-67 of up to 8% and positive p53 immunostaining. His cabergoline dose was adjusted to 0.5 mg PO daily and he was also started on Sandostatin 20 mg IM monthly as well as appropriate hormonal replacement of the other deficient pituitary hormonal axes. Follow up imaging revealed stability of the lesion. The patient continues to do clinically well and actively follows with endocrinology and neurosurgery with serial brain MRIs and laboratory workup. Discussion The histological and biochemical characteristics of aggressive prolactin secreting tumors has been reported to be of minimal utility in distinguishing benign from malignant lesions. Tumors can only be diagnosed as carcinomas after they have metastasized and they can only be classified as aggressive after treatment failure or unusual growth, which creates a disadvantage for the prognosis and management of these patients. Clinicians are in need of better guidelines that can help them identify the rare cases that might warrant more aggressive clinical interventions beyond dopamine agonists such as surgery, radiation, temozolomide, somatostatin receptor agonists and others, with the hope of delaying or preventing the development of metastasis. Case reports of atypical presentations of aggressive prolactinomas such as the one here presented, can help broaden our understanding of the predictable signs of poor prognosis. Presentation: No date and time listed