Renal angiomyolipoma

Case contributed by Frank Gaillard
Diagnosis certain

Presentation

Right flank pain.

Patient Data

Age: Adult

CT kidneys

ct

Pre and post-contrast CT through the kidneys demonstrates a large fatty mass arising from the lateral aspect of the right kidney. There is a very prominent vessel centrally associated with central areas of soft tissue attenuation, some of which enhance, but other areas do not. These presumably represent areas of haemorrhage. 

This patient went on to have a right partial wedge nephrectomy.

MACROSCOPIC APPEARANCE: Specimen consists of a wedge of kidney measuring 5.5 X 4 X 2.5 cm that came with a soft fatty nodule bulging on its surface, measuring 13 X 9.5 X 8 cm, weighing in total 430 g. The external capsule is smooth and shows tan-purple haemorrhage. Cross-section of the nodule shows yellowish fatty tissues with focal haemorrhage that is surrounded by a well-defined capsule. The tumour partially replaces the renal parenchyma and extends into the peri-renal fat.

MICROSCOPY: It has typical features of angiomyolipoma with smooth muscle spindle cells, at times with an altered ovoid morphology, admixed and blending with thick-walled blood vessels and tumour adipose tissue. Occasional compact sheets of the smooth muscle mesenchymal component are present, with degenerative nuclear atypia. There is no significant mitotic activity and no evidence of malignant transformation.

FINAL DIAGNOSIS:

  • angiomyolipoma of the kidney.
  • tumour size = 13cm.
  • acute haemorrhage within tumour.

Case Discussion

This case demonstrates typical appearances of a large angiomyolipoma. Best seen on the post-contrast images is a very large vessel which accounts for this tumour's predilection for spontaneous haemorrhage. 

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