Association of leptomeningeal carcinomatosis in carcinoma of the breast with infiltrating lobular carcinoma. An autopsy study.

We analyzed the autopsy records of 261 patients with breast carcinoma, who died at The Institute of Oncology, Ljubljana, Yugoslavia, for the presence of metastases to the central nervous system, particularly for the presence of leptomeningeal carcinomatosis. Metastases to the central nervous system were found in 41 (18.1%) of 226 patients who had metastatic cancer. In 24 cases (10.6%), metastases were seen in brain parenchyma; in 11 cases (4.9%), only dura mater was involved, and in six cases (2.6%), leptomeningeal carcinomatosis was found. All patients with leptomeningeal carcinomatosis showed some symptoms of central nervous system involvement while alive. The patients died between 2 weeks and 2 months after the onset of central nervous system symptoms. Four of six patients with such a complication presented with locally advanced or disseminated carcinoma on the first admission. With regard to histologic findings, three patients had infiltrating lobular carcinoma, two had infiltrating ductal carcinoma, and one had mixed infiltrating lobular and ductal carcinoma, with a metastasizing lobular component. Metastases to the brain parenchyma were found exclusively in infiltrating ductal carcinoma. We stress that infiltrating lobular carcinoma represents a distinctive type of breast cancer with an unusual propensity to disseminate into leptomeninges, as this occurred in almost 14% of all cases of infiltrating lobular carcinoma in our series in contrast to a 1% incidence in cases of infiltrating ductal carcinoma.