Malignant prolactinoma: case report and review of the literature.

BACKGROUND: Malignant prolactinomas are rare events. To date, only 14 patients with metastases in- or outside the central nervous system have been reported. CASE DESCRIPTION: 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. DISCUSSION: 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.