Meningeal carcinomatosis.

An anatomopathologic study of 18 cases of pure meningeal carcinomatosis is presented. In five of these cases, the brain, spinal cord, choroid plexuses, cerebral vessels, and prevertebral soft tissues, including the lumbosacral nerve plexuses and ganglia, were examined microscopically in an attmept to determine the routes of tumor spread. Our results suggest that the malignant cells reach the cerebrospinal leptomeninges via perineural, endoneural, and perivascular lymphatics and sheaths through the intervertebral and possibly cranial foramina. Involvement of the choroid plexuses appears to be secondary to, rather than the avenue for, leptomeningeal carcinomatosis, with the tumor cells reaching the choroid plexuses via the perivascular sheaths of choroidal vessels. Leptomeningeal carcinomatosis was the only manifestation of metastatic spread beyond regional lymph nodes in about 40% of all reported cases in which this information is available. This implies that radiation or other forms of local therapy to the cerebrospinal leptomeninges may provide an effective means of palliation in many of these cases.