Humoral hypercalcemia of malignancy in squamous cell carcinoma of the skin: parathyroid hormone--related protein as a cause.

The second most common cause of hypercalcemia is humoral hypercalcemia of malignancy (HHM), a condition associated with increased mortality. Although hypercalcemia is usually seen in squamous cell cancers, only 13 cases have been described in association with squamous cell skin cancer, and only 5 of these had characteristics of HHM. We report a case of hypercalcemia due to squamous cell skin cancer confined to the chest wall in a 67-year-old semi-comatose patient. Aggressive treatment with intravenous fluid hydration, furosemide, and etidronate corrected the hypercalcemia. A thorough workup ruled out bone metastasis and confirmed increased parathyroid-related protein, the hallmark of HHM. After regaining consciousness, the patient refused further therapy and subsequently died.