RecruitingStudy in Patients With Breast Cancer Leptomeningeal MetastasisTraditional clinical trials in patients with breast cancer leptomeningeal disease (LMD) are challenging as patients often have a rapidly progressive course and prognosis is poor, making meeting standard eligibility difficult. Furthermore, there is limited information about the biology of LMD. The investigators thus propose a study that is as inclusive as possible, which will allow the investigators to collect biospecimens and clinical outcomes to learn more about LMD biology, but still potentially provide benefit for patients, by providing patients rapid diagnostics and multi-disciplinary treatment recommendations.