Isolated Leptomeningeal Metastasis of Breast Cancer During Neo-Adjuvant Chemotherapy: A Case Report

The incidence of symptomatic brain metastasis from breast cancer ranges from ~10% to 15%. Brain parenchymal metastasis comprises most of this and has been studied more extensively, whereas isolated leptomeningeal carcinomatosis (LC) is exceedingly rare. The diagnosis is most commonly made by lumbar puncture and cerebrospinal fluid (CSF) cytology, although it is persistently negative in about 10% of patients, and hence its pre-mortem diagnosis remains difficult and controversial. There are limited therapeutic options available making the prognosis abysmal. It has been reported that locally responsive breast cancers on chemotherapy can develop CNS metastasis; the blood-brain barrier and the unique brain microenvironment are hypothesized to promote distinct molecular features in such CNS metastases. We present a 37-year-old female with a large triple-negative, node-positive grade three invasive ductal carcinomas with Ki-67 70%. Despite the local response to neoadjuvant chemotherapy, she developed rapidly worsening multiple neurological symptoms. MRI brain showed leptomeningeal enhancement and CSF cytology results were negative with inconclusive other CSF studies. The patient deteriorated very rapidly and a post-mortem diagnosis of isolated LC was made. The notable aspects of this case include the development of a rapidly progressive isolated LC despite the good local response to the chemotherapy, which requires further studying. As the currently available diagnostic and therapeutic tools have limitations, research can be critical in providing better outcomes for this fatal disease.