Renal angiomyolipoma

Case contributed by Jose Ignacio Aragon


Routine check-up.

Patient Data

Age: 30 years
Gender: Female

Ultrasound of the abdomen demonstrates a round, well defined, hyperechoic nodule, with mild peripheral vascularity, located in the cortex of the upper pole of the left kidney.

Case Discussion

Angiomyolipoma (AML) of the kidney is a benign neoplasm composed of a variable proportion of adipose tissue, smooth muscle, and blood vessels derived from perivascular epithelioid cells. Typically they are asymptomatic, unilateral and discovered in middle-aged women. Symptoms develop in 68%–80% of patients when tumor size reaches 4 cm or great, the most severe are related to rupture, with secondary hematoma.

AMLs tend to occur sporadically or related to tuberous sclerosis. 80% of the patients with tuberous sclerosis will have one or more AMLs.

Echo pattern is related to the proportion of fat, smooth muscle and blood vessels. The more fat present, the nodule will be more echogenic, the more fibrous or vascular components, it'll become more hypoechoic.

The classic appearance of AML is a small rounded intraparenchymal or exophytic hyperechoic lesion with variable appearance. The casting of a shadow can be seen occasionally. If there's a rupture, it can become very heterogeneous and expanding, even with stranding of the perirenal fat.

Differential diagnosis includes renal cell carcinoma, oncocytoma and even metastases.

Generally, no treatment is required, unless ruptured, in which case may need surgical management.

Coauthors of this case include Dr Jose R Zuniga.

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