Malignant prolactinoma: case report and review of the literature.

Malignant prolactinomas are rare events. To date, only 14 patients with metastases in- or outside the central nervous system have been reported. We present a patient who developed a metastasis to the cauda equina, which is the first case documented with MRI. A giant prolactinoma in this 51-year-old man was partially removed by a transcranial approach. After radiotherapy and treatment with bromocriptine, the patient had a remission for 3 years. Thereafter, a sacral intraspinal tumor was diagnosed. Because of increasing prolactin levels not responding to bromocriptine and a radiologically suspected intrasellar tumor, we operated transsphenoidally first and found only fibrous tissue. We performed a sacral laminectomy and almost totally removed an intradural tumor. Histopathology and immunohistochemistry confirmed the diagnosis of a prolactinoma metastasis. The patient received radiotherapy and bromocriptine and has no evidence of recurrent tumor or metastases after a follow-up of 38 months, thus being the second reported patient with long-term remission of the disease. We review the literature on this topic and try to establish common features of the course of this rare malignant disease and the efficacy of therapy in the cases reported hitherto.