PATH-42. METASTATIC ADENOID CYSTIC CARCINOMA OF BREAST WITH BRAIN METASTASES AND LEPTOMENINGEAL DISEASE

Abstract INTRODUCTION Adenoid cystic carcinoma (ACC) of the breast rarely metastasizes to the brain and leptomeninges. ACC is a rare type of breast cancer, accounting for less than 0.1% of cases. It is usually triple negative, but has a good prognosis when it is confined to the breast. Lymph node involvement is uncommon, occurring in less than 2% of cases, and distant metastases to the brain are extremely rare. Leptomeningeal disease has not been reported yet. Case: In this case, we describe a 57-year-old woman diagnosed with triple-negative ACC of the right breast, which had spread to the axillary lymph nodes and distant metastases to the lung. The diagnosis was confirmed by biopsies of both metastatic sites. The patient received vinorelbine and cisplatin treatment for 11 cycles followed by right needle localized lumpectomy. While awaiting for the next steps in treatment she was admitted to the hospital for altered mental status, saddle anesthesia, and urinary incontinence. Neuraxis MRI revealed numerous hemorrhagic and non-hemorrhagic brain metastasis with diffuse leptomeningeal disease. Cerebrospinal fluid analysis confirmed leptomeningeal disease with positive cytology for atypical epithelioid malignant cells. The patient underwent whole brain radiation and focal radiation treatment to specific areas of leptomeningeal disease. Although she initially improved after the first month of radiation, her condition deteriorated rapidly, preventing the initiation of the next line of treatment with high-dose methotrexate or capecitabine. DISCUSSION Adenoid cystic carcinoma of the breast is exceedingly rare however with a very good overall prognosis. It is uncommon for ACC to spread to regional lymph nodes, and even rarer for distant metastasis. Brain metastasis is also infrequently reported. There are no documented cases of metastatic ACC with leptomeningeal disease, so there is no consensus on the best course of treatment.