Primary necrotizing arteritis of the main renal artery presenting as accelerated renovascular hypertension

Presented is a unique case of accelerated hypertension in a 26-year-old black man. Clinically, the patient was found to have a left renal artery lesion and lateralizing renal vein renins. At surgery, a stenosing lesion was found in the artery supplying the upper pole of the left kidney. This was caused by a densely fibrotic mass involving the main renal artery. Microscopy revealed a necrotizing arteritis with no other arteries involved. This case of primary necrotizing arteritis of the main renal artery appears to represent a new entity because of its pathological and clinical differences with the known forms of large vessel arteritis. It is possible that this may represent a particularly acute and necrotizing stage of Takayasu's aortitis, or an extremely rare case of classical periarteritis nodosa confined solely to the main renal artery. The renin tissue assays document the hyperreninemia produced by arterial stenosis. The differential diagnosis of the lesion is considered, and the pathophysiology of hypertension due to large vessel arteritis is discussed.