Angiomyolipoma
🧩 Angiomyolipoma (AML) is a benign hamartomatous tumour of the kidney, made up of fat, smooth muscle, and blood vessels.
⚠️ While usually asymptomatic, large AMLs can rupture and bleed (Wunderlich syndrome).
📖 About
- Benign renal parenchymal tumour – often incidental finding on imaging.
- Classic association with Tuberous Sclerosis Complex (TSC) 🧠.
- Bleeding risk rises when size >4 cm or when vascular components are prominent.
🧬 Aetiology
- Composed of a mixture of adipose tissue, smooth muscle, and thick-walled vessels.
- Hamartomatous origin (disorganised growth of normal elements).
- Malignant transformation is rare but has been described in atypical cases.
👩⚕️ Clinical Features
- More common in women, peak in 4th–5th decade.
- Often asymptomatic – discovered on ultrasound/CT for another reason.
- When symptomatic:
- Flank or abdominal pain.
- Palpable mass.
- Microscopic or macroscopic haematuria 🚨.
- Large lesions can rupture → retroperitoneal haemorrhage with hypotension, shock (Wunderlich syndrome) 💉.
🧪 Investigations
- CT Abdomen: ✅ Diagnostic test of choice – shows fat attenuation within the mass (classic hallmark).
- Ultrasound: Hyperechoic lesion due to fat content (but not specific).
- MRI: Helpful if CT is inconclusive or to differentiate from renal cell carcinoma.
- TSC screening: If AML is multiple/bilateral, consider workup for tuberous sclerosis.
🩺 Management
- 🎯 Conservative: Small (<4 cm), asymptomatic → monitor with regular imaging.
- 💉 Embolisation: Minimally invasive, first-line for bleeding AMLs or symptomatic cases.
- 🔪 Surgery:
- Partial nephrectomy if localised and symptomatic.
- Radical nephrectomy only if uncontrollable bleeding or malignancy can’t be excluded.
- 📏 Size threshold: >4 cm = higher risk of rupture → consider prophylactic intervention.
🌟 Clinical Pearls
- Think “fat in the kidney” on CT → Angiomyolipoma until proven otherwise.
- Multiple AMLs in a young patient → screen for TSC (look for seizures, skin lesions, cognitive impairment).
- New targeted therapy (mTOR inhibitors like everolimus) can shrink AMLs in TSC patients.
📚 References
