Bilateral Wilm’s Tumour

Findings and interpretation:

• There are two large, heterogeneous, solid masses located in the right and left aspects of the retroperitoneum, respectively. Both masses demonstrate the claw sign at each kidney, indicating renal parenchymal origin. Both kidneys appear distorted and compressed by their respective masses.
• Both appear heterogeneously hyperintense on T2, and are demarcated by a thin T2 hypointense pseudocapsule. An area of T2 hypointensity in the right sided mass which appears hyperintense on the T1 sequence represents a focus of previous haemorrhage.
• Both masses show heterogeneous high signal on the DWI sequence with corresponding low ADC values indicating restricted diffusion.
• The masses show heterogeneous enhancement on the post-contrast images.
• The right renal vein shows a filling defect on the post-contrast sequence, indicating thrombosis.

Pertinent negative findings:

• There is no invasion of the left renal vein or IVC.
• There is no evidence of liver metastases.

The findings represent synchronous malignant tumours arising from both kidneys with near identical features.

Principal diagnosis:

Bilateral Wilm’s Tumours

Differential diagnosis:

• Lymphoma- extremely unlikely as the imaging features are not consistent with this diagnosis.
• Renal cell carcinoma- extremely unlikely as this is encountered far less than Wilm’s tumour in children, especially at this age. It is usually significantly smaller than Wilm’s tumour at presentation. It would not be bilateral.

Management:

Alert referring physician of findings.

Recommend CT thorax to search for lung metastases and complete staging.

Ultrasound guided biopsy may be performed for histological diagnosis.

Discussion at paediatric oncology MDT.

Findings and interpretation:

• There are confluent, bilateral and symmetric FLAIR and T2 signal hyperintensities in the periventricular white matter, particularly around the frontal horns and trigones of the lateral ventricles; these show a striated ‘tigroid’ appearance.
• There is sparing of the subcortical U fibres.
• The striations show low signal intensity on the T1 images.
• There is some reduction in the volume of deep white matter.

Pertinent negative findings:

• There is no optic nerve enlargement.
• There is no restricted diffusion.

The findings represent dysmyelination of the deep white matter.

Principal diagnosis:

Metachromatic leukodystrophy.

Differential diagnosis:

Other leukodystrophies such as:

• Pelizaeus Merzbacher disease
• Autosomal recessive spastic ataxia

Management:

Alert referring physician of findings.

Retroperitoneal fibrosis

Findings and interpretation:

CT KUB

• There is bilateral moderate to marked hydronephrosis and hydroureter of the proximal third of both ureters.
• There is an ill-defined soft tissue retroperitoneal mass at the level of L3-L4 which surrounds the aorta and IVC.

CT urography:

• On the portal venous phase, the mass is enhancing and encases the aorta and IVC without invasion or displacement. The left common iliac artery is non-enhancing, indicating thrombosis.
• There has been interim placement of bilateral nephrostomy catheters, with resolution of the previously noted hydronephrosis on both sides.
• On the urographic phase both ureters are medially displaced into the mass; there is focal luminal stenosis at that level.

The findings represent a fibro-inflammatory mass which involves and obstructs both ureters causing obstructive nephropathy. The mass has also caused thrombosis of the left common iliac artery. Enhancement of the mass indicates active inflammation.

Principal diagnosis:

Retroperitoneal fibrosis

Differential diagnosis:

• Aortitis
• Retroperitoneal lymphoma: however, this would typically cause displacement of the aorta/IVC

Management:

Recommend vascular surgery referral for arterial thrombosis.

Recommend discussion at connective tissue disease MDT to plan further management (corticosteroids are usually indicated in these cases).

Septic emboli

Findings and interpretation:

• There are multiple, bilateral nodular areas of consolidation in both lungs, in a peripheral and basal distribution. Some of these exhibit central cavitation.
• There are widespread areas of increased parenchymal lucency in both lungs, signifying centrilobular emphysema.
• The CT pulmonary angiogram demonstrates filling defects in multiple 2^nd and 3^rd order pulmonary arteries bilaterally. Some of the filling defects are within arteries that lead to consolidations, demonstrating the ‘feeding vessel’ sign.
• There are multiple enlarged mediastinal lymph nodes, which appear reactive in nature.
• There are scattered bilateral pulmonary nodules, seen mostly in the lower lobes.
• There is a minimal right basal pleural effusion.

The findings represent infected emboli in the pulmonary arterial system causing infectious consolidation / infarction.

Principal diagnosis:

Septic pulmonary emboli

Differential diagnosis:

• Pulmonary infarcts
• Pneumonia

Management:

Urgently contact referring physician and inform of findings to immediately initiate treatment (usually with broad spectrum IV antibiotics).

Recommend echocardiography to investigate source of emboli (infectious endocarditis).

Ventriculitis and brain abscesses

Findings and interpretation:

• There is bilateral periventricular and deep white matter FLAIR and T2 hyperintensity, which is also seen outlining the lateral ventricles.
• There is isointense material lying in a dependent position in both lateral ventricles as well as the third ventricle on the FLAIR and T2 images. This is causing dilatation of the 3^rd and lateral ventricles.
• There are two rounded lesions in the left periventricular white matter, which appear hyperintense on the fluid sensitive sequences and show smooth, complete ring enhancement. One of these is bulging into the ipsilateral lateral ventricle.
• The lesions appear bright on the DWI images with corresponding low ADC values, signifying restricted diffusion.
• Restricted diffusion is also seen within the dependent fluid in the lateral ventricles and along the ventricular ependyma.
• Mild lepto and pachymeningeal enhancement is also noted

Incidental findings:

• There is bilateral mastoiditis.

The findings represent a CNS infection with meningitis and brain abscesses, one of which has ruptured into the left lateral ventricle causing ventriculitis.

Principal diagnosis:

Brain abscesses and ventriculitis.

Differential diagnosis:

• Ependymal tumour spread: however this is typically nodular; marked diffusion restriction is not a feature of CNS malignancy.
• Intraventricular haemorrhage: however the signal characteristics do not match blood products.

Management:

Urgently contact referring physician and inform of findings.

Recommend urgent neurosurgical referral.

Tuberous sclerosis complex

Findings and interpretation:

Abdomen and pelvis:

• Both kidneys are significantly enlarged, with the renal parenchyma almost completely replaced by heterogenous tissue mostly comprised of macroscopic fat with interspersed soft tissue density and blood vessels. The masses are exerting mass effect and compressing the abdominal contents centrally.
• There is a hyperdense rim surrounding the outer aspect of the right kidney. Moreover, the arterial phase images show a saccular structure within the right kidney which enhances to the same degree as the blood pool, and again matching the blood pool on the portal venous phase.
• There is a round, well defined, homogeneous soft tissue lesion arising from the left renal parenchyma. This forms an angular interface with the renal parenchyma proper.
• There are small, scattered, well defined lesions in the liver which show macroscopic fat density.
• There are innumerable focal sclerotic bony lesions in the visualized thoracic, lumbar and sacral spine, as well as at the right acetabulum.
• There are numerous cysts visualized in the lung bases.

Brain:

• There are multiple intraventricular calcified nodules in both lateral ventricles, as well as the third ventricle.
• There are multiple, scattered hypodense lesions in the subcortical and periventricular white matter, as well as the cortical regions of the cerebral hemispheres bilaterally. These lesions show no surrounding oedema or mass effect.

Pertinent negative findings:

• There are no cardiac masses (rhabdomyoma).
• There are no ventricular masses (subependymal giant cell astrocytoma).

Both kidneys are largely infiltrated by angiomyolipomas, which mostly replace the renal parenchyma. There is a pseudo-aneurysm within the right kidney, arising from angiomyolipomatous transformation. This has undergone active bleeding, resulting in a peri-nephric haematoma.

The solid mass in the left kidney is likely a lipid poor component of the angiomyolipoma. The fatty lesions in the liver represent angiomyolipomas. The cystic lesions in the lung represent lymphangioleiomyomatosis- like changes.

The lesions in the brain represent subcortical tubers. These, along with the bony lesions and angiomyolipomas, represent benign hamartomatous lesions involving multiple organ systems. The constellation of findings is diagnostic for tuberous sclerosis complex.

Principal diagnosis:

Tuberous sclerosis complex.

Differential diagnosis:

The soft tissue mass within the left kidney may represent RCC rather than lipid poor angiomyolipoma.

Management:

Urgently alert referring physician of findings.

Recommend referral to interventional radiology for embolisation of the pseudo-aneurysm.

Biopsy of the left renal mass may be discussed at the relevant MDT once the active issues have been managed.