Differential diagnosis of hypercalcemia in renal malignancy.

We report a case of large cell B-cell lymphoma of the kidney associated with humoral hypercalcemia of malignancy. A 70-year-old man presented with renal failure and hypercalcemia. After the workup, the patient was thought to have renal cell carcinoma and underwent radical nephrectomy. The pathologic evaluation showed a large cell lymphoma with a B-cell phenotype. Reevaluation of the patient's serum revealed a high calcitriol level with low parathyroid hormone and parathyroid hormone-related protein levels, consistent with the final pathologic findings. The differential diagnosis of hypercalcemia in renal malignancy is presented.