Breast cancer and synchronous multiple myeloma as a diagnostic challenge: Case report and review of literature.

Multiple myeloma is a hematological malignancy, which sometimes creates difficulties in diagnosis, based on the presence of monoclonal protein in serum/urine and plasmocyte infiltration in the bone marrow, and on the other hand, synchronous cancers are also a diagnostic challenge. We present a case report of a patient with concurrent breast cancer and multiple myeloma. A 68-year-old woman was admitted to the hospital with diagnosis of left breast cancer in first stage of the disease. In the past, she had had several episodes of thrombocytopenia, leucocytosis, and mild anaemia, which were followed by hematologist in outpatient setting. She was operated and started adjuvant chemotherapy. During treatment, episodes of hematological abnormalities were observed. After completion of the chemotherapy for breast cancer, the patient was observed and short time after that multiple myeloma was diagnosed as a synchronous cancer. Patient was first treated for breast cancer, then subsequently for multiple myeloma (2 lines therapy: CTD and VMP). We describe diagnostic problems with multiple myeloma; however, they could be caused by curation of breast cancer, which might have supressed the proliferation of plasmocytes and could delay the diagnosis. All symptoms of multiple myeloma were interpreted as a secondary effect of chemotherapy. Review of the literature shows the clinical approaches in such situations.