BMET-38. PROSTATIC CARCINOMA METASTATIC TO THE NERVOUS SYSTEM: PARENCHYMAL AND PROBLEMATIC CASES

Abstract

Demographics of metastatic disease coming to biopsy or surgical resection in the nervous system have changed dramatically over the years, due to the advent of treatment with non-interventional techniques such as stereotactic radiosurgery. Patients with known metastatic nervous system involvement, especially if multifocal, are most likely to be treated without histological confirmation, changing which cases are most likely to come to neurosurgical attention. Namely, single metastases of unknown origin, single presumed metastases in patients with known previous diagnosis of malignancy(s) from tumors which seldom spread to the nervous system, and dural/epidural masses requiring emergent spinal decompression are more likely to prompt surgical intervention. Metastatic prostatic carcinoma is encompassed in the two latter categories. We reviewed our databases for all cases in which metastatic prostatic carcinoma was strongly clinically suspected and/ or diagnosed at biopsy, 2000-present. As expected 16 cases were dural-based tumors, but 5 were intraparenchymal in pituitary region, right frontal and occipital lobes, cerebellum, right temporal lobe and right thalamus. The latter has been reported only rarely. Conversely, patients with known histories of prostatic carcinoma and suspected metastases were identified having neurocytoma, skull base chordoma, ectopic pituitary adenoma to clival region (detailed in Clin Neuropathol. 2012;31(1):24-30), anaplastic meningioma, and undifferentiated malignancies. Two more presented morphologically-challenging diagnoses, including a small cell neuroendocrine variant of prostatic carcinoma and one extremely poorly differentiated with loss of several diagnostic immunohistochemical markers. We conclude that metastatic prostatic carcinoma to the nervous system continues to provide pre-biopsy diagnostic challenges in modern day practice, due to the mixed dural and parenchymal involvement that can be seen, coupled with the frequency with which a diagnosis of previous prostatic carcinoma has been rendered in a patient presenting with new intracranial and/or dural mass(es). Our cohort suggests that intraparenchymal prostatic metastases are likely more frequent than cited incidences.