Synchronous Bilateral Breast Cancer Complicated by Humoral Hypercalcemia of Malignancy—A Case Report—

Abstract

A 68-year-old woman visited our hospital with a left breast mass. Computed tomography (CT) revealed a left breast tumor, left axillary lymphadenopathy, and right breast tumor. She was diagnosed with synchronous bilateral breast cancer after needle biopsy. Laboratory tests revealed hypercalcemia (12.3 mg/dL), but PET-CT showed no bone metastasis or other distant metastasis. Therefore, we assessed PTHrP levels (18.8 pmol/L) and made the final diagnosis of breast cancer with humoral hypercalcemia of malignancy (HHM). After treatment for hypercalcemia, she underwent surgery for the breast cancers. Postoperatively, she had no elevation in serum calcium and PTHrP levels and had no recurrence for 6 months. Few cases of breast cancer with HHM have been reported. We believe that surgical treatment is a useful therapy for resectable breast cancer with HHM.