Renal cell carcinoma associated with sarcoidlike tissue reaction. A 60-year-old man was referred to our institution with the diagnosis of sarcoidosis. Because of several months' complaint of right flank pain and weight loss, the patient had consulted his local physician. After an extensive workup revealed only cholelithiasis, he underwent a cholecystectomy for presumed chronic cholecystitis. At the time of operation, biopsy of several liver nodules and peripancreatic nodes revealed noncaseating granulomas, consistent with sarcoidosis. On initial examination at our institution, the patient had microhematuria. A chest roentgenogram demonstrated multiple pulmonary nodules, an abdominal computed tomographic scan showed an indeterminate left renal mass, and magnetic resonance imaging of the spine revealed abnormal signals in the body of T-12. Open-lung biopsy showed an adenocarcinoma with clear cell features, likely of renal origin. The patient was diagnosed as having a metastatic renal carcinoma associated with a sarcoidlike tissue reaction. Although noncaseating granulomas have been reported in association with other malignant lesions, to our knowledge this is the first report of such an association with renal carcinoma. In addition, this case illustrates several points. First, sarcoidosis is a multisystem disorder with protean extrapulmonary manifestations. In fact, all our patient's findings could have been attributed to sarcoidosis. Second, noncaseating granulomas occur with many types of processes, including infections, chemical exposures, and, as in this case, neoplasms. Thus, noncaseating granulomas are not pathognomonic for sarcoidosis. Third, sarcoidosis is a clinical diagnosis that cannot be based on histologic findings alone. 