[A Case of Bone Marrow Carcinomatosis Associated with Breast Cancer with Anemia and Thrombocytopenia Successfully Treated with Aromatase Inhibitor Therapy].

The patient was a 61-year-old woman who presented to the hospital with the chief complaints of anemia and thrombocytopenia. There was a mass in her left breast, and a needle biopsy with pathology revealed invasive ductal carcinoma, which was HR-positive and HER2-negative. A PET scan revealed multiple bone metastases, which were confirmed on bone marrow biopsy, leading to the diagnosis of bone marrow carcinomatosis. As the patient was in good general condition, an aromatase inhibitor(AI)therapy was selected. Rapid improvements in her hemoglobin level and platelet count were observed. At 19 months after the start of treatment, we were able to perform a left mastectomy with left axillary lymph node dissection. The histological evaluation of her response to treatment was Grade 2a, and severe lymph node metastasis was observed. The patient continued to receive the AI postoperatively. Thirty-two months after the start of treatment, there was no evidence of cancer on clinical imaging. Although it is rare for bone marrow carcinomatosis to occur, as in the present case, it is also notable that the patient had been in long-term remission with consistent AI therapy.