What happened, in summary

This 50-year-old Azeri woman had recently completed surgery and chemotherapy for left breast invasive ductal carcinoma when she returned to the hospital with weakness and lethargy. Her breast cancer was T2N2M0, Stage IIIA, and triple-negative. She had undergone left modified radical mastectomy within the previous 2 months, followed by TAC chemotherapy with docetaxel, doxorubicin hydrochloride, and cyclophosphamide. Radiotherapy was being considered but had not yet started. Two days after her last chemotherapy round, she became weak and lethargic. Examination showed a normally healed mastectomy incision, no local recurrence, no lymphadenopathy, normal heart and lung findings, no abdominal mass, and no extremity deformity or missed fracture. Laboratory tests showed severe neutropenia and hypercalcemia, with serum calcium 12.9 mg/dL. She received broad-spectrum antibiotics, G-CSF, and isolation for neutropenia, along with isotonic fluids, furosemide, and corticosteroids for hypercalcemia. Because hypercalcemia in breast cancer can suggest bone metastasis, doctors checked lumbar, chest, and pelvic X-rays plus a whole-body scan. These showed no bone metastases. Her parathyroid hormone level was markedly elevated at 285.3 pg/mL, and ultrasound found a vascular right lower parathyroid mass measuring 26 × 15 × 10 mm. She underwent subtotal parathyroidectomy with removal of the right lower adenoma. Calcium fell to 9.7 mg/dL, symptoms improved, pathology confirmed parathyroid adenoma, and follow-up calcium levels stayed normal. Her cancer status remained Stage IIIA under ongoing treatment planning. The episode also shows that hypercalcemia in a patient with breast cancer is not always caused by metastasis; in her case, a treatable parathyroid adenoma explained the metabolic problem.