[A Case of Perirenal Non-Specific Lymphadenitis Resected by Laparoscopic Operation for the Possibility of Malignancy].

Various types of tumors, including benign tumors, arise from the renal parenchyma or renal capsule, but it is difficult to predict the histological type preoperatively. Here, we report a case of perirenal non-specific lymphadenitis resected laparoscopically. A 79-year-old man with a history of diabetic mellitus and noninvasive bladder cancer had an incidentally-detected enhanced mass in contact with the surface of the left kidney. Given the possibility that the tumor was malignant, we resected the mass laparoscopically. Intraoperative findings revealed that the tumor did not invade the renal parenchyma, and it could be easily resected. Microscopic findings showed that the tumor consisted of inflammation of a lymph node, lymphoid follicles with hyperplasia of germ center and granulomatous inflammation with giant cells, and there was no malignant finding. Despite various additional examinations, the specific cause of the lymphadenitis was not clarified, leading to a final diagnosis of non-specific lymphadenitis. To our knowledge this is the first report about perirenal non-specific lymphadenitis difficult to distinguish from perirenal malignant tumor in preoperative computed tomography imaging.