Laterality of Pancreatic Metastases from Renal Cell Carcinoma: An Anatomical Perspective from the Left Kidney and Tail of the Pancreas

Abstract

IntroductionSurgical findings have shown left kidney renal cell carcinoma (RCC) spreads to the pancreas in an isolated fashion. The pancreas is not a common metastatic site for cancers known to spread via the systemic circulation or lymphatics so no anatomical explanation for these findings has been described. Current literature dictates that rapidly growing neoplasms can transgress renal fascial planes. We hypothesize that there is both a lymphatic and vascular track traversing and within Gerota's fascia which provides local communication between the left kidney and tail of the pancreas. The lymphatic and vascular systems in the perirenal and pararenal spaces are undocumented.ObjectivesThe objective of this study is to propose an anatomical explanation for the spread of RCC from the left kidney to the proximal tail of the pancreas and establish its laterality in regards to preferential metastatic spread.MethodsFour fresh‐frozen cadaveric specimens and 20 fixed cadaveric specimens are in the process of retroperitoneal dissection. Left sided perirenal and pararenal lymphatic vessels and lymph nodes will be identified using GEWF (glacial acetic acid, ethanol, distilled water, and formaldehyde) and immunohistochemistry; monoclonal antibody D2–30 (a lymphatic endothelial marker). Vasculature will be identified under a surgical microscope and further characterized using immunohistochemistry; polyclonal antibody CD31(a pan‐endothelial marker). A chart review of patients with RCC metastasis (from the London Health Sciences Centre, London Ontario) is currently being developed into a retrospective case‐control study to determine frequency of RCC metastasis to the pancreas.ResultsDissection of fresh‐frozen cadavers has revealed vascular bundles that emerge from the fibrous kidney capsule to enter the fat‐filled perirenal space. These bundles contain arteries, veins and lymphatics. Microdissection has revealed a high concentration of these vascular networks in the superior pole of the left kidney, converging on the left adrenal gland. These networks are also seen to traverse the perirenal space, contained within Gerota's fascia. Small venules are seen piercing Gerota's fascia and running within this multilaminar connective tissue. We predict that the chart review will show left kidney tumours metastasizing more often to the tail of the pancreas possibly by means of these described networks.ConclusionsUnderstanding the vascular and lymphatic pathways between the left kidney and the tail of the pancreas will help determine dissection planes and the extent of radical resection surgery with a curative intent. The anatomical description of existing pathways between these structures and the perirenal and pararenal spaces may aid in the anatomical understanding of the spread of RCC. It may also have implications where local resection of tumours is considered.