A Case of Recurrent Breast Cancer with Humoral Hypercalcemia of Malignancy

Abstract

Here, we have reported a case of a 45-year-old woman with primary breast cancer. She had a tumor measuring 6 cm in her right breast and a lymph node measuring 1 cm in her right axilla, both of which were palpable. Core needle biopsy revealed the following : invasive ductal carcinoma, nuclear grade 3, ER(-), PgR(-), HER2(1+), and Ki-67 : 85%. Imaging examination revealed no distant metastasis. The patient was diagnosed with cT3N1M0 cStage IIIA breast cancer and underwent a mastectomy after neoadjuvant chemotherapy. The histological therapeutic effect was grade 1a. One month after operation, local and axillary lymph node recurrence and multiple lung metastases were observed ; hence, eribulin treatment was initiated. At the end of the first course, hypercalcemia was observed (serum Ca level : 15.3 mg/dl) ; however, contrast-enhanced CT and PET-CT examination revealed no bone metastasis. Intact PTH levels were normal (5 pg/mL), while PTHrP levels were elevated (19.5 pmol/L) ; hence, we considered that the cause was humoral hypercalcemia of malignancy (HHM). Although the serum Ca level was normalized with bisphosphonate treatment, treatment for breast cancer could not be resumed because her disease progressed rapidly and her general condition worsened.