Presentation
Left loin pain and fever with elevated white cell count and CRP. Not diabetic.
Patient Data
MRI to confirm CT findings
Well-defined cystic mass in the midpole left kidney (rim of reduced T2 signal) with surrounding parenchymal swelling/edema and extensive edema in the perinephric fat. Rim enhancement pointing laterally towards the loin. No solid component. Nonenhancing filling defect in the left renal vein and an inferomedial branch (communicating with left paraspinal veins) consistent with thrombosis.
Similar findings on CT with mural swelling in the left renal pelvis and upper ureter as well as filling defect in the left renal vein and tributaries. Abscess confirmed at nephrectomy.
Case Discussion
Renal abscess or carbuncle is usually seen in diabetic patients and is hematogenous in origin rather than ascending from the bladder as with pyleonephritis. In severe cases it can cause thrombophlebitis in the draining veins (i.e. the renal vein and tributaries as in this case). It is important to differentiate this situation from renal cell carcinoma with renal vein invasion (often the clinical parameters will dictate this). Treatment is antibiotics and percutaneous drainage prior to anticoagulation.