[Malignant hypercalcemia after treatment of breast cancer].

A premenopausal woman developed hypercalcemia 30 months after treatment for infiltrating breast cancer. After bone metastases had been excluded, primary hyper parathyroidism was suspected. A parathyroid adenoma was removed and histologically confirmed. Hypercalcemia persisted, associated with low plasma phosphate and severely depressed plasma parathormone (PTH) levels. Further investigations showed liver metastases from the primary breast cancer and also secretion of a PTH-like substance. Anti-tumoral treatment was effective on the liver metastases and also normalized calcemia and the PTH-like substance, demonstrating the existence of a paraneoplastic syndrome related to the secretion of a PTH-like substance by disseminated liver metastases of primary breast cancer.