Pediatric Case of Renovascular Hypertension and Multivessel Aneurysms Associated with Suspected Fibromuscular Dysplasia

Fibromuscular dysplasia (FMD) is a rare, non-atherosclerotic, non-inflammatory vascular disease leading to arterial stenosis, aneurysm formation, and vascular remodeling. It is exceptionally rare in children, and reports of multivessel involvement complicated by renal failure are limited.

The patient is a 5-year-old child. For the past 3 years, the child has been experiencing abdominal pain, recurrent fever up to 38.0°C, constipation, weakness, malignant arterial hypertension reaching 220/155 mmHg, azotemia, severe anemia of mixed origin, subcompensated metabolic acidosis, growth retardation, and secondary hyperparathyroidism.

Abdominal CT findings: hepatomegaly, portal hypertension, acute cholecystitis, pericholecystitis, gallbladder kinking, hypoplasia of the right kidney, a mass lesion, subcapsular hematoma of the left kidney, post-drainage changes of the left abdominal cavity, free fluid in the pelvic cavity, aneurysmal dilatation of both renal arteries, as well as the left common and external iliac arteries with mural calcifications.

Renal ultrasound findings:

·       Kidneys are located in their typical anatomical positions.

·       The left kidney is enlarged: 9.1 × 3.5 cm. Parenchymal thickness 1.2 cm. Pelvicalyceal system – 2.1 cm. Pyramids are hyperechoic and thickened. No differentiation between cortical and medullary layers. The renal capsule is thickened. Subcapsular hypoechoic fluid-like content encasing the kidney circumferentially, with maximum thickness of 1.2 cm. At the lower pole, there is a rounded soft tissue lesion measuring 8 cm in diameter, heterogeneous due to hypoechoic inclusions, with relatively well-defined but irregular borders. On color Doppler, intralesional vascular flow is preserved.

·       The right kidney is reduced in size: 4.5 × 1.7 cm. Parenchymal thickness 0.6 cm. Pelvicalyceal system 0.6 cm. Hyperechoic thickened pyramids, loss of corticomedullary differentiation. On color Doppler, vascular pattern is preserved but diminished peripherally.

·       Urinary bladder empty due to catheterization.

Impression (Ultrasound/CT): renal mass (possible Wilms’ tumor), subcapsular hematoma of the left kidney, diffuse changes of both kidneys, dysmetabolic nephropathy, right kidney hypoplasia.

Cranial CT with contrast: no vascular abnormalities detected.

Acute kidney injury (injury stage) due to stenosis of the proximal right renal artery; aneurysms of the right and left renal arteries, left common femoral artery, and left internal iliac artery with mural calcifications (suspected fibromuscular dysplasia?); secondary atrophy of the right kidney; structural changes in both kidneys; bilateral subcapsular renal hematomas.

Because of progressive azotemia and hyperkalemia, the child was started on hemodialysis, but tolerance remained poor. Despite ongoing therapy, the child’s condition is only moderately stable. Considering the chronicity of the disease, the diagnosis evolved from acute kidney injury to chronic kidney disease, end-stage renal disease (ESRD).

A multidisciplinary council involving surgeons, vascular surgeons, oncologists, and urologists recommended peritoneal catheter implantation with simultaneous left nephrectomy.

The risks of kidney transplantation (renal hemorrhage, vascular thrombosis, thromboembolism, acute rejection crisis, poor prognosis up to lethal outcome), as well as the possible genetic predisposition of the child to thrombotic complications, were repeatedly explained to the parents.

Given the absence of a potential living donor, the child was recommended for inclusion in the kidney transplant waiting list (Republic of Kazakhstan and Republic of Belarus).

At present, no technical issues with peritoneal dialysis drainage or inflow are noted. Ultrafiltration remains satisfactory.

We present a unique pediatric case of suspected fibromuscular dysplasia with renal artery stenosis, multiple large-vessel aneurysms, malignant hypertension, and progression to chronic kidney disease requiring renal replacement therapy. Early recognition and multidisciplinary management are essential in such rare, life-threatening presentations.