Malrotation of Kidney Ectopia and Spontaneous Renal Vein Thrombosis.

Renal ectopia and malrotation are uncommon congenital anomalies that arise from abnormal kidney ascent and rotation during embryologic development. Although often discovered incidentally, these structural variations may alter venous drainage and predispose to stasis and thrombosis. Renal vein thrombosis (RVT) is rare in adults and usually occurs secondary to nephrotic syndrome, malignancy, dehydration, or hypercoagulable disorders. The coexistence of renal malrotation, ectopia, and spontaneous RVT in an otherwise healthy adult is exceptionally unusual. A 35-year-old woman presented with severe right-lower-quadrant abdominal pain, nausea, and fever, initially raising concern for appendicitis. Laboratory results revealed severe microcytic anemia with reactive thrombocytosis. Contrast-enhanced computed tomography demonstrated a malrotated ectopic left kidney located in the iliac fossa with associated left RVT. Comprehensive evaluation for thrombophilia, autoimmune disease, and malignancy was negative, while iron studies confirmed marked iron-deficiency anemia. The patient was treated with blood transfusion and anticoagulation, resulting in complete clinical and radiologic resolution after one year of follow-up. This case illustrates how congenital renal vascular anomalies and hematologic abnormalities may interact to produce thrombosis. Altered venous outflow from the ectopic kidney likely caused local stasis, while iron-deficiency anemia contributed to a transient hypercoagulable state through reactive thrombocytosis and endothelial dysfunction. Clinicians should consider RVT in the differential diagnosis of atypical abdominal or flank pain when imaging reveals renal positional anomalies. Early recognition and anticoagulation can preserve renal function and prevent unnecessary surgical intervention.