Leptomeningeal Disease as an Initial Presenting Manifestation in Breast Cancer.

Leptomeningeal disease (LMD) occurs in less than 5% of breast cancer patients. Rarely, patients present with LMD at diagnosis. We report a case of a 59-year-old female who presented with lower back pain, radicular neuropathy with lower extremity weakness, and was found to have diffuse LMD. Workup was initiated to evaluate the etiology of LMD and later involved iliac bone biopsy showed metastatic adenocarcinoma consistent with breast carcinoma. Patient received radiation therapy followed by abemaciclib with letrozole and responded well with the treatment.