Hypercalcemia and breast cancer related to parathormone-like secretion by liver metastases.

A premenopausal woman developed hypercalcemia 30 months after treatment for infiltrating breast cancer. After bone metastases had been excluded, primary hyperparathyroidism was suspected. A parathyroid adenoma was removed and histologically confirmed. Hypercalcemia, associated with low plasma phosphate and severely depressed plasma parathormone (PTH) levels, persisted. Further investigations showed liver metastases from the primary breast cancer and also secretion of a PTH-like substance. Antitumoral 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.