Case 15
Renal angiomyolipomas and cortical cysts in Tuberous Sclerosis
Bilateral loin pain
This 43 year old female presented with a bilateral loin pain of recent onset. A renal ultrasound demonstrated multiple small anechoic and hyperechoic lesions bilaterally. CT was performed to elucidate.
Pre and post intravenous contrast CT images are shown. Multiple small cysts are visible on the CT. Some appear more solid. The data analysis shows pixels of fat density within the lesion.
A head CT image is also included from the same patient.
Findings
Multiple simple cortical cysts in both kidneys
Heterogeneous, solid 2.5 cm mass in right lower pole, which contains areas of fat density
Calcified subependymal hamartomas in the brain
Diagnosis
Tuberous Sclerosis
- Renal angiomyolipoma
- Multiple renal cortical cysts
- Subependymal hamartomas
Differential
Adult polycystic kidney disease
Neurofibromatosis
Von Hippel-Lindau disease
Discussion
Tuberous sclerosis (Bourneville Disease, Epiloia) is an autosomal dominant neuroectodermal disorder with low penetrance; thus the majority have no family history.
The main features are:
- Epilepsy (80%)
- Mental retardation (60%)
- Adenoma sebaceum (30%)
Renal imaging features
- Angiomyolipomas (AML)
- The commonest renal feature, they may be multiple and bilateral. They may become very large,or bleed spontaneously. They are typically hyperechoic on ultrasound, and CT can confirm the diagnosis if the fat can be demonstrated (pixel less than - 30HU), as in this case. The image demonstrated the pixel mapping feature of te GE scanner - it shows the Hounsfield units for each pixel in the area of interest which has been placed over the AML, and several pixels are of fat density.
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- Multiple Cysts
- Multiple AMLs are commoner, but in occasional cases (as here) the cysts are the predominant feature and may even be indistinguishable from adult polycystic kidney disease.
- Renal failure and hypertension
- May result from the extensive involvement by the cysts on AML.
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Cerebral imaging features
Brain imaging with CT and MRI demonstrates the dysplastic features:
- Subependymal hamartomas
- Frequently calcified, these lesions are clearly seen along the lateral surface of the lateral ventricles on CT, but may be less obvious on MR due to signal loss from the calcification (see example image above).
- Cortical hamartomas
- Hypodense cortical lesions which may be increased in intensity on T2W MR imaging.
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- Heterotopic white matter
- Hypodense areas of abnormal white matter, usually more obvious on MR, with areas of high signal on T2W images.
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- Giant cell astrocytoma
- A large benign tumour that characteristically occurs in the region of the foramen of Munro in 10% of patients. It may become quite large and may degenerate into a high grade astrocytoma.
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Other sites of involvement
The lungs may be involved with interstitial fibrosis that closely resembles lymphangioleiomyomatosis.
Optic phakoma is a retinal hamartoma that occurs in over 50% of patients.
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