Idiopathic Renal Infarct in a Healthy Adult With an Accessory Renal Artery: A Case Report.

Renal infarction is an uncommon and frequently underdiagnosed condition caused by the acute interruption of renal arterial blood flow. Its clinical presentation often mimics renal colic, and laboratory findings may be nonspecific, leading to delayed or missed diagnosis. Although embolic and thrombotic etiologies are most commonly implicated, idiopathic renal infarction remains rare. We report the case of a 45-year-old previously healthy man who presented with sudden-onset left flank pain radiating to the left upper quadrant, associated with nausea and abdominal discomfort. He had no history of cardiovascular disease, trauma, thrombophilia, or autoimmune disorders. Physical examination revealed left costovertebral angle tenderness. Laboratory evaluation demonstrated mild leukocytosis and microscopic hematuria without inflammatory marker elevation. Contrast-enhanced computed tomography of the abdomen and pelvis revealed multifocal wedge-shaped hypoenhancing areas in the left kidney consistent with renal infarction, secondary to filling defects in the main left renal artery. An accessory left renal artery supplying the inferior pole was noted. Autoimmune and thrombophilia workup was negative. The patient was treated with anticoagulation using unfractionated heparin followed by apixaban. Follow-up imaging demonstrated partial recanalization of the renal artery with no progression of infarction and preserved renal function. Idiopathic renal infarction should be considered in patients presenting with acute flank pain when initial evaluation for nephrolithiasis is negative. Early contrast-enhanced imaging is crucial for diagnosis. Prompt anticoagulation can prevent progression and preserve renal function.