Diffuse Leptomeningeal Carcinomatosis

Abstract

Invasion of the brain parenchyma in the central nervous system by blood-borne metastatic foci is not uncommonly seen. A rapidly fatal result may occur with a purely subarachnoid and leptomeningeal invasion, apparently lymph-borne by peripheral perineural pathways. The literature yields 83 such cases in which autopsy revealed no blood-borne metastatic nodules in the brain substance, choroid plexus or meninges. Two additional cases of this leptomeningeal carcinomatosis are reported here, one of peribronchial, the other of gastric origin. Clinically, the condition may resemble tuberculous meningitis but without fever and with sterile cerebro-spinal fluid in which tumor cells may be found. Focal signs are rare as contrasted with blood-borne metastatic brain tumor. Pathologically, the primary lesion is more frequently gastric than pulmonary or mammary as contrasted with the blood-borne brain metastases. Pathological diagnosis is made on the basis of microscopic finding of a diffuse subarachnoid dissemination of cancer cells over the brain, spinal cord and intradural portions of cranial and spinal nerves with a variable spread into all cerebral and cerebellar fissures and along subpial intracor-tical perivascular spaces. Evidence supporting the theory of infiltration of perineural spaces at the primary lesion with secondary centripetal invasion is presented. Survival and spread of the cancer cell in the subarachnoid space is evidently related to a dependence upon glucose as a metabolite.