A large unilateral renal artery aneurysm in a young child.

The case of a 13-month-old boy with fibromuscular dysplasia (FMD) presenting with a large saccular aneurysm of the left renal artery and renovascular hypertension is reported. Renal and intrarenal arteries showed numerous small aneurysms alternating with stenoses. All arterial lesions were localized to the left kidney. After left nephrectomy, the patient's blood pressure normalized. Histopathologic examination of the arteries disclosed changes typical of medial fibroplasias, the most frequently described form of FMD in children. This diagnosis is rewarding as it represents a surgically curable cause of severe hypertension.