This 64-year-old man who denied trauma history presented with progressive right fl ank pain for two weeks and experienced an episode of large amount of gross haematuria preceding right fl ank pain. Hypotension (72/45 mmHg) was noted at arrival with haemoglobin only 3.0 gm/dl. Physical examination revealed a distended abdomen with a mild bruise over right fl ank (Fig 1A). Renal ultrasonography (Fig 1B) showed a fl uid accumulation between Gerorta’s fascia (arrow) and renal capsule (arrow heads). Emergent pre-contrast MDCT with reformation (Fig 2) showed a large heterogeneous hyperdense mass at right upper kidney (arrowheads) with ipsilateral dilated ureter (arrow). Before this episode, acquired haemophilia A had been diagnosed for 14 months accompanied by the past histories of nephrolithiasis and chronic kidney disease stage IV. His baseline Factor VIII activity was 150 Bethesda Units. In recent eight months, activated partial thromboplastin time (aPTT) was maintained around 100 seconds along with recurrent bleeding episodes including cutaneous ecchymoses, calf and scapula haematomas, and intermittent haematuria which were rescued by consecutive threeor four-dose recombinant Factor VIIa (rFVIIa) 90 μg/Kg repeatedly at Haemophilia Clinic. Under the impression of haemophilic renal pseudotumour (haematoma), he received aggressive blood transfu-