Neoplastic and Non-neoplastic Proliferative Disorders of the Peri-renal Space: Cross-sectional Imaging Findings

Venkateswar R. Surabhi, MD , Christine Menias, MD , Srinivasa R. Prasad, MD , Ankitkumar H. Patel, MD , Arpit Nagar, MD , Neal C. Dalrymple, MD

The perirenal space, located between the anterior and the posterior renal fasciae, is shaped like an inverted cone with an apex that extends into the iliac fossa. Perirenal tumors and pseudotumors primarily orig-inate either from the kidney or as part of a systemic disease process and have characteristic histopathologic features and biologic behavior. The lesions may be classified on the basis of their distribution and imaging features as solitary soft-tissue masses (renal cell carcinoma, lymphangioma, hemangioma, and leiomyoma), rindlike soft-tissue le-sions (lymphoma, retroperitoneal fibrosis, and Erdheim-Chester dis-ease), masses containing macroscopic fat (angiomyolipoma, liposarco-ma, myelolipoma, and extramedullary hematopoiesis), and multifocal soft-tissue masses (metastases, plasma cell tumors). Because of overlap in imaging findings among these diverse perirenal lesions, a defini-tive diagnosis in most cases can be established only at histopathologic analysis. However, an imaging pattern-based approach may facili-tate the diagnosis and optimal management of perirenal tumors and pseudotumors.