Extra-osseous intracranial metastasis from prostatic carcinoma.
Metastasis from adenocarcinoma of the prostate to the central nervous system is a rare finding. In the English-language literature only a few cases have been reported . Among the reported cases, most tumors were located at the skull base with involvement and destruction of the bone. Further extension of these tumors into the cavernous sinus lead to neurological symptoms such as cranial nerve palsies and has been described for prostate cancer metastasis occurring late in the disease process [1;3]. There has been a recent increase in presentations of leptomeningeal metastases from prostate cancer detected by CT and MR imaging. Due to its cumulative presentation in men with hormone refractory prostate cancer and systemic chemotherapy, leptomeningeal metastases are thought to be either correlative with advanced dissemination or secondary to new systemic treatments. The prognosis of leptomeningeal metastases is poor, with a median survival time of 15 weeks . Intraaxial metastases from prostate cancer are even more uncommon with only six publications reporting such findings [2;4-6;8-9]. Lynes et al. reviewed 4421 patients with prostate cancer of whom only 8 (0.2%) patients had brain metastases. Six of these were diagnosed post-mortem . The majority of metastases were located supratentorially .
Radiological diagnosis based on CT and MR-imaging is often not specific for metastatic disease. In our case negative findings in bone scintigraphy and the absence of bone involvement was included in the assessment of MRI findings. Thus, in spite of the disseminated disease in our patient, radiological diagnosis favored meningioma rather than metastasis. The tumor appeared similar to cavernous sinus meningiomas with extension to the middle fossa along the sphenoid wing. Intraoperatively the tumor showed clear border to the temporal lobe with compression of a temporobasal vein.
In summary our case demonstrates that intracranial metastases from prostatic adenocarcinoma may mimic extraaxial tumors (e.g. meningioma) on CT and MR imaging. Thus, in cases of a milder clinical manifestation, this may result in a "wait and see" attitude with potential harm for the patients. Therefore, in disseminated prostate cancer, atypical cerebral metastasis has to be considered in regard of further treatment decisions.
Contributed by Andrea M. Faymonville, MD, Christoph Kabbasch, MD, Tobias Blau, MD, Roland Goldbrunner, MD, Stefan Grau, MD