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Case 1

Case 1 Model Answer:

Bilateral paragangliomas (carotid body tumours)

Findings and interpretation:

CT:

  • There are two, well defined soft tissue masses in the neck. Both lie anteromedial to and are intimately related to the internal carotid artery.
  • The larger one on the left side lies at the bifurcation of the internal and external carotid arteries. It shows avid contrast enhancement with relative hypo-enhancement at the centre.
  • The smaller one on the right side lies at the level of C2, and also shows avid contrast enhancement.

MRI:

  • Both lesions are heterogeneously hyper-intense to muscle on T2 with areas of low signal within.

The findings represent hypervascular masses with non-aggressive characteristics.

 

Principal diagnosis:

Bilateral carotid body tumours (paragangliomas).

 

Differential diagnoses:

  • Glomus vagale paraganglioma (the right sided lesion, as it lies higher than expected for a carotid body lesion).
  • Carotid space neurofibroma / schwannoma (these are not usually as vascular).
  • Enlarged lymph nodes (these are not usually as vascular).

 

Management:

Refer for discussion at ENT/neuro-endocrine MDM.

These are usually managed by surgical excision.  

 

Author’s note:

Splaying of the internal and external carotid arteries is a characteristic feature of these lesions; However, it is not seen in this case because of the atypical location and small size of the lesions. Salt and pepper appearance on MRI is also typical of these lesions, but is only seen when they are large in size.  

Case 1 Your Answer:

No Answer Submitted

Case 2

Case 2 Model Answer:

Findings and interpretation:

  • There are geographic ground glass opacities, seen mostly in the mid and lower lung zones. This shows a mosaic attenuation appearance, likely caused by air trapping.
  • There are subpleural and apical reticular opacities and septal thickening, more pronounced on the left side, and sparing the lower lung zones and bases.
  • There is pre and para-tracheal, as well as peri-aortic mediastinal lymphadenopathy.

Pertinent negative findings:

  • There are no pleural effusions / areas of consolidation.

 

The findings represent an interstitial lung disease, which is likely causing air trapping due to bronchiolar inflammation, as well as mild apical fibrotic changes.

 

Principal diagnosis:

Hypersensitivity pneumonitis

 

Differential diagnosis:

  • Bronchiolitis obliterans
  • Infectious bronchiolitis

 

Management:

Obtain expiratory phase HRCT to confirm air trapping.

Review clinical notes / contact referring physician to elucidate possible history of exposure to organic allergen.

Case 2 Your Answer:

No Answer Submitted

Case 3

Case 3 Model Answer:

Findings and interpretation:

  • There is a cluster of dilated small bowel loops in the right side of the abdomen. There are also freely mobile dilated small bowel loops with a generalised distribution in the abdominal cavity.
  • The third and fourth part of the duodenum do not follow their usual course to the left side of the abdomen; instead, the duodenum remains on the right and the second part of the duodenum enters into the cluster of dilated bowel loops. There is a transition point as tapering bowel exits the cluster at a more caudal level. 
  • The distal small bowel is collapsed.
  • The clustered loops located in the pelvis show thickened and edematous walls.
  • There is peri-hepatic and peri-splenic, as well as pelvic free fluid.

Pertinent negative findings:

  • There is no pneumatosis intestinalis / portal venous gas.
  • No extra-luminal air to suggest perforation.

 

The findings represent small bowel obstruction caused by internally herniated and strangulated small bowel loops. Some of the bowel loops show impending ischemia. There is underlying congenital malrotation of the small bowel.

 

Principal diagnosis:

Right paraduodenal hernia on a background of intestinal malrotation, complicated by strangulation. 

 

Differential diagnosis:

  • Small bowel volvulus
  • Transmesenteric internal hernia

 

Management:

Urgently contact referring physician and inform of findings. These cases are usually managed by urgent laparotomy.

Case 3 Your Answer:

No Answer Submitted

Case 4

Case 4 Model Answer:

Findings and interpretation:

CT:

  • There are multiple focal sites of hypo-attenuation indicating vasogenic oedema in the cerebral hemispheres bilaterally.

 

MRI:

  • There are multiple round lesions which appear hypointense on the T1 images and show heterogeneous intensity on the T2 images. The lesions show surrounding high T2 and FLAIR signal intensity.
  • Some of the lesions show hypointense concentric rings on the T2 / FLAIR images.
  • The lesions asymmetrically involve the basal ganglia and cerebral hemispheres bilaterally, and mostly lie at the cortico-medullary junction.
  • The lesions demonstrate mild diffusion restriction.

Pertinent negative findings:

  • The lesions are not calcified / haemorrhagic.

 

There are multiple lesions in the brain which show significant surrounding inflammation, which in this clinical context are most likely of infectious etiology.

 

Principal diagnosis:

Toxoplasmosis

 

Differential diagnosis:

  • Lymphoma: this is more likely to be single and show greater diffusion restriction
  • Other infectious disease such as tuberculosis / cryptococcosis
  • Metastases

 

Management:

Obtain contrast enhanced sequence.

Alert referring physician of findings.

Case 4 Your Answer:

No Answer Submitted

Case 5

Case 5 Model Answer:

Findings and interpretation:

  • There is a mixed cystic and solid soft tissue mass in the hand, insinuating between the thenar eminence and other intrinsic muscles of the hand with mass effect.
  • The solid component of the mass is heterogeneously hyperintense on T2, with similar T1 intensity to muscle.
  • The solid component is avidly enhancing on the postcontrast images.

Pertinent negative findings:

  • There is no invasion of the adjacent bones.

 

The findings represent an aggressive neoplastic mass of musculoskeletal origin.

 

Principal diagnosis:

Synovial sarcoma

 

Differential diagnosis:

  • Malignant peripheral nerve sheath tumour
  • Extraskeletal Ewing’s sarcoma
  • Other soft tissue sarcoma

 

Management:

Alert referring physician of findings.

Refer for sarcoma MDT to discuss further investigation for staging purposes (bone scan and CT thorax / abdomen / pelvis), as well as biopsy in conjunction with orthopaedic surgeons in order to avoid seeding of tissues that will not be resected.

Case 5 Your Answer:

No Answer Submitted

Case 6

Case 6 Model Answer:

Findings and interpretation:

Non-enhanced CT:

  • The liver is enlarged and markedly hyperdense, with irregular margins and left lobe hypertrophy. There is a rim of peri-hepatic fluid.
  • There are multiple hypodense lesions seen throughout the liver.
  • No spleen is visualised. The spleen has been surgically removed.
  • All visualised bones are osteopaenic, and show expansion of the medullary space with increased trabeculation and thinning of the cortices.
  • There are multiple calcified ovoid lesions in the retroperitoneum and at the porta hepatis.
  • There is a rim of soft tissue extending anteriorly from the sacrum.

Portal venous phase CT:

  • There is peri-portal oedema with non-enhancement of the main portal vein and its first order tributaries. There is extensive collateralisation around the main portal vein.
  • The liver parenchymal lesions are hypo-enhancing on the portal venous phase.

Pertinent negative findings:

  • The pancreas is of normal density.

Incidental findings:

  • There are multiple simple cysts in the left kidney.

 

The skeletal manifestations and hyperdensity of the liver indicate extramedullary haematopoiesis and repeated blood transfusions, respectively. The calcified lesions in the abdomen and soft tissue around the sacrum also likely represent extramedullary haematopoiesis. This is explained by the presence of a haemolytic anaemia requiring multiple blood transfusions, and resulting in secondary haemochromatosis.

The spleen has been resected, presumably because of massive splenomegaly.

The liver is cirrhotic as a result of secondary haemochromatosis. The multiple liver lesions most likely represent multi-focal hepatocellular carcinoma, which has invaded the portal vein and resulted in portal vein thrombosis.

 

Principal diagnosis:

Thalassaemia with secondary haemochromatosis and liver cirrhosis with multifocal hepatocellular carcinoma and portal vein thrombosis

 

Differential diagnosis:

The lesions in the liver may also represent extramedullary haematopoiesis.

 

Management:

Alert referring physician of findings.

Refer for discussion at hepatobiliary MDT to discuss further imaging by four-phasic CT or triphasic liver MRI for further characterisation of liver lesions.

Biopsy of the liver lesions to differentiate from EMH.

Case 6 Your Answer:

No Answer Submitted
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