Bilateral thoracic renal arteries in a 29-year-old undergoing evaluation of a right retroperitoneal mass.

Thoracic renal arteries (TRAs), defined as renal arteries originating above the diaphragmatic hiatus from the descending thoracic aorta, represent an exceptionally rare anomaly reported in less than 0.1% of the general population. Traditionally, they are predominantly described as unilateral right-sided variants with origins at the T10-T12 vertebral levels. We report the case of a 29-year-old female with an indeterminate right retroperitoneal mass requiring image-guided biopsy. Upon review of cross-sectional imaging for preprocedural planning, contrast-enhanced CT incidentally revealed bilateral TRAs. On the right, there was a single, dominant thoracic renal artery arising from the aorta at the bottom of T12 vertebral body. The left kidney had a dominant left renal artery in the typical location at the top of L2, with a smaller accessory thoracic renal artery arising from the aorta at the midportion of T11. Embryologically, the presence of TRAs reflects the persistence of cranial mesonephric arterial segments that normally regress as the kidneys ascend. While unilateral TRAs have been sporadically documented, bilateral thoracic origins remain extraordinarily uncommon. Such high-level renal artery origins pose a heightened risk for iatrogenic injury during retroperitoneal procedures and may have implications for thoracic endovascular aortic repair (TEVAR), open thoracoabdominal surgeries, and transplant planning. Recognizing the potential for bilateral TRAs is crucial for interventional radiologists and vascular surgeons. Meticulous imaging review, including arterial-phase reconstructions, serves to avoid complications such as hemorrhage, inadvertent arterial occlusion, or renal ischemia. This case underscores the importance of considering aberrant vascular anatomy in patients undergoing interventions.