KILT syndrome revealed by right iliac fossa pain in an 11-year-old boy: A case report.

Kidney and Inferior Vena Cava abnormalities with Leg Thrombosis syndrome, an acronym for kidney and inferior vena cava abnormalities with leg thrombosis, is a rare congenital condition that predisposes young patients to deep venous thrombosis. We report on the case of an 11-year-old boy with a recent diagnosis of pulmonary tuberculosis who presented with right iliac fossa pain and inability to walk because of a painful flexed right lower limb. Initial ultrasound was inconclusive for appendicitis because the appendix was not visualized due to bowel gas; it showed no peritoneal fluid or intraperitoneal fat infiltration, but the left kidney was not identified. Contrast-enhanced computed tomography excluded acute appendicitis and abdominal tuberculosis and revealed left renal agenesis with compensatory right renal hypertrophy, agenesis of the infrarenal inferior vena cava and bilateral common iliac veins, left external iliac vein agenesis with a small right external iliac vein, extensive collateral venous drainage, and thrombosis of the right internal iliac, common femoral, femoral, deep femoral, and lumbar veins. Targeted Doppler ultrasound confirmed right iliofemoral venous thrombosis. The association of renal agenesis, inferior vena cava and iliac venous agenesis, and lower-limb venous thrombosis established the diagnosis of Kidney and Inferior Vena Cava abnormalities with Leg Thrombosis syndrome. Anticoagulant therapy was initiated with favorable clinical evolution. This case highlights the importance of considering congenital venous anomalies in children presenting with atypical abdominal or groin pain and lower-limb symptoms and emphasizes the complementary role of computed tomography and Doppler ultrasound in diagnosis.