Multiple isolated brain metastases from a Duke's B colon carcinoma.

Brain metastases from colorectal carcinomas are very uncommon and are almost uniformly seen in the setting of advanced, systemic disease. We describe a unique case of multiple, isolated brain metastases occurring from a Duke's B carcinoma of the sigmoid colon. Careful staging at two intervals at which clinical brain metastases were found did not disclose additional evidence of systemic disease. The cascade mechanism thought to be involved in the development of systemic metastases is reviewed, and a possible alternate route is suggested for direct access by tumor cells to the brain via Batson's vertebral plexus.