<prompt> A 40-year-old male complains of hematuria and an aching pain in his flank. Laboratory data show normal BUN, creatinine, and electrolytes. Hemoglobin is elevated at 18 gdL and serum calcium is 11 mgdL. A solid renal mass is found by ultrasound. The most likely diagnosis isPolycystic kidney diseaseRenal carcinomaAdrenal adenomaUrolithiasis  <response>: Renal carcinoma is twice as common in men as women and tends to occur in the 50- to 70-year age group. Many patients present with a hematuria or flank pain, but the classic triad of hematuria, flank pain, and a palpable flank mass occurs in only 10 to 20 of patients. Paraneoplastic syndromes such as erythrocytosis, hypercalcemia, hepatic dysfunction, and fever of unknown origin are common. Surgery is the only potentially curable therapy; the results of treatment with chemotherapy or radiation therapy for nonresectable disease have been disappointing. Interferon a and interleukin 2 produce responses but no cures in 10 to 20 of patients. The prognosis for metastatic renal cell carcinoma is dismal. 