Carcinomatous meningitis associated with infiltrating lobular carcinoma of the breast.

The records of 365 patients with advanced carcinoma of the breast were examined to identify those with CNS involvement. Nineteen (5.2%) developed parenchymal cerebral deposits and 10 (2.7%) developed meningeal infiltration during the course of their disease. Parenchymal cerebral deposits were almost exclusively associated with infiltrating duct carcinoma (95%) and meningeal infiltration (carcinomatous meningitis) was almost exclusively associated with infiltrating lobular carcinoma. Meningeal infiltration occurred late in the course of advanced disease and was associated with diffuse involvement of the bone marrow and abdominal structures.