ACTH-Producing Breast Cancer: A Patient Report

Ectopic ACTH secretion in the setting of breast cancer is extremely rare but when present affects both the tumor's behavior and the incidence of complications. The patient, a 58-year-old woman, first presented with a mass in her left breast as well as multiple osseous metastases and a right femur fracture. Laboratory data revealed a hypokalemic alkalosis. Her plasma ACTH level was elevated. She was diagnosed with breast cancer with ectopic ACTH secretion, and underwent a left mastectomy and axillary lymph node dissection. Histological examination demonstrated a poorly differentiated neuroendocrine carcinoma with ectopic ACTH secretion. Although the signs and symptoms of ectopic ACTH secretion from a breast cancer are frequently subtle, the recognition of ectopic ACTH secretion from breast cancer is important for patient management. The ectopic secretion of ACTH in the setting of cancer is well demonstrated in small-cell lung carcinoma, neuroendocrine tumors of the lung, thymus, gastrointestinal tract, islet cell carcinoma of the pancreas, pheochromocytoma and medullary thyroid carcinoma (Isidori and Lenzi, 2007).