A complex renal cyst was incidentally detected on ultrasound in a patient following which he underwent a CT for an insurance workup. What is the likely diagnosis?
C. Perinephric cyst
D. Renal cell carcinoma
Answer- B. Angiomyolipoma
- In the given CT image, the renal mass is containing fat content, which is suggestive of angiomyolipoma, which is a fat containing benign renal neoplasm.
- Angiomyolipoma is the only benign renal tumor that is confidently diagnosed on cross-sectional imaging. The presence offat (confirmed on non-enhanced thin-cut CT by a value of -20 Hounsfield Units (HU) or less) within a renal lesion is considered the diagnostic hallmark. Findings of more than 20 pivels with ottenaation less than -20 HU and of more than5 pixels with attenaation less than -30 HU hsve been shown to have a positive predictive value of 100%. Liltrasonography shows a well-circumscribed, highly echogenic lesion with shadowing. On angiography (or CT-angiography) aneurysmal dilation is found in 50’% of angiomyolipomas. The size of the aneurysms has been reported to correlate with the risk of rupture.