Collision renal cell papillary and medullary carcinoma in a 66-year-old man.

The Case: The patient is a 66-year-old male who presented to his primary care physician with a 3-week history of painless gross hematuria. He underwent a renal ultrasound that showed a left kidney mass. A computed tomography (CT) scan of the abdomen and pelvis confirmed the presence of a left mid-anterior renal mass measuring 5.3 × 5.9 × 7.4 cm, with thrombus extension into a branch of the left renal vein coursing through the mass, but no extension into the main left renal vein. Excretory phase images showed extrinsic compression of the left intrarenal collecting system at the level of the mass. A previous CT scan of the pelvis, done 6 months earlier to evaluate flank pain, showed only slight lobulation in this area. A staging chest x-ray was unremarkable. The patient is a lifelong nonsmoker and has no personal or family history of malignancy, hematologic disorders, or sickle cell hemoglobinopathy. He underwent left radical nephrectomy with dissection of the renal vein. An outside pathology report described a unifocal, 7-cm, pT3aNx, Fuhrman grade 3-4/4 renal cell carcinoma (RCC) with rhabdoid features juxtaposed to papillary RCC. There was macroscopic extension into the renal vein, renal pelvis, and perinephric fat, and microscopic extension into the renal pelvis and perinephric fat. Postoperative laboratory evaluations were pertinent for a white blood cell count of 7.5 × 103/μL, absolute neutrophil count of 5.4 × 103/μL, hemoglobin level of 14.1 g/dL, platelets of 224 × 103/μL, creatinine level of 1.2 mg/dL, and calcium level of 9.1 mg/dL. Lactate dehydrogenase level was not available.