Model Answers
Case 1
Case 1 Model Answer:
Arnold Chiari I malformation with syringomyelia
Findings and interpretation:
- The cerebellar tonsils are herniating caudally into the foramen magnum to a small extent, and show peaking of the inferior aspect.
- There is effacement of the cisterna magna and crowding of the brainstem structures at the foramen magnum.
- The cervical spinal cord is uniformly enlarged, showing fluid signal intensity on the T2 sequence with low signal on T1 centrally, with a thin rim of surrounding tissue.
- There is a small cyst in the medulla showing T2 signal matching that of CSF, with signal void matching that of CSF on the FLAIR sequence.
Pertinent negative findings:
- There is no evidence of obstructive hydrocephalus.
- No enhancement of the cervical spinal cord on the post-contrast images.
Incidental findings:
- There are degenerative cervical spine changes with loss of disc height and T2 signal intensity, as well as multi-level central bulge.
The findings represent a congenital structural malformation of the posterior fossa structures, with associated cystic abnormality of the cervical spinal cord caused by obstruction of CSF flow. The smaller localized cyst indicates separate hydromyelia while the central collection of CSF represents syringomyelia.
Principal diagnosis:
Arnold Chiari I malformation with associated syringomyelia.
Differential diagnosis:
- Hydromyelia rather than syringomyelia
- Chiari 1.5/2 malformation
- Basilar invagination
Management:
Alert referring physician of findings.
Recommend neurosurgical referral.
Case 1 Your Answer:
Case 2
Case 2 Model Answer:
Post Transplant Lymphoproliferative Disorder
Findings and interpretation:
- There is moderate to marked splenomegaly with prominent splenic varices at the hilum of the spleen. There are multiple small hypo-enhancing lesions scattered throughout the spleen, mostly uniform in size.
- Surgical clips are seen at the medial border of the liver allograft. Multiple hypo-enhancing lesions that are also small and uniform in size are seen scattered throughout the liver.
- There are multiple enlarged coeliac group and peri-aortic lymph nodes with low density centres. The largest one lies adjacent to the origin of the SMA and measures 3 – 5 cm in diameter.
- Some of the small, hypo-enhancing lesions are also seen in both kidneys, to a much lesser extent than the liver and spleen.
- There is a subcutaneous lesion which also demonstrates peripheral enhancement and hypodensity of the centre, located anterior to the xiphisternum.
- There are multiple scattered lytic bony lesions located in the vertebral bodies of the lumbar and lower thoracic spines.
Pertinent negative findings:
- There is no thickening of the small bowel.
In correlation with the surgical history provided, the findings most likely represent a lympho-proliferative disorder involving the solid visceral organs, axial skeleton and lymph nodes at multiple sites. The splenic varices indicate portosystemic collaterals due to portal hypertension.
Principal diagnosis:
Post-transplant lymphoproliferative disorder.
Differential diagnosis:
- Multi-system tuberculosis (the bony lesions do not fit with this diagnosis)
- Sarcoidosis
- Multiple myeloma (bony lesions only)
Management:
Alert referring physician of findings.
Refer for oncology MDT to discuss further management / treatment options.
Case 2 Your Answer:
Case 3
Case 3 Model Answer:
Osteogenesis imperfecta
Findings and interpretation:
Radiographs at 1 week of age:
- There is a fracture at the diaphysis of both the right and left femora.
- There is a bowing deformity of the left femur and both tibiae. Bowing deformity is also demonstrated in the ribs and the left humerus.
- There is a fracture of the right radius.
Radiographs at 2 years of age:
- More pronounced bowing deformity is demonstrated in the femora and tibiae.
- There is pronounced callus formation surrounding the left femoral diaphysis at the site of the previous fracture. A lucent line at this site indicates mal-union of the fracture.
- There are horizontal sclerotic lines at the metaphyses of the long bones.
- There is generalised osteoporosis.
The findings indicate a generalised, congenital musculoskeletal abnormality causing weakening of the long bones with multiple consequent fractures. Growth lines are demonstrated in the long bones as sequelae of bisphosphonate therapy.
Principal diagnosis:
Osteogenesis imperfecta (most likely type III)
Differential diagnosis:
- Non-accidental injury
- Hypophosphatasia
Management:
Inform referring physician of findings if diagnosis not already known, as well as active issues (such as mal-union of the femoral fracture).
Refer for discussion at orthopaedic MDT with regards to further management.
Case 3 Your Answer:
Case 4
Case 4 Model Answer:
Findings and interpretation:
- There is a large, well defined mass extending from the left upper quadrant to the mid-abdomen. This appears to originate from the pancreatic tail and body as it is inseparable from pancreatic parenchyma.
- This is exerting mass effect on the splenic vein, causing compression with resultant splenic varices extending anterior to the mass. There is also mass effect on other abdominal structures, most prominently on the liver and pancreas which are displaced medially and the kidney which is displaced posteriorly.
- The mass is made up of locules separated by septations, with the individual locules containing fluid material of varying density. There are a few soft tissue components at the walls peripherally.
- The septae and soft tissue components within the mass show enhancement on the post-contrast images.
Pertinent negative findings:
- There are no calcifications in the mass.
- There are no enlarged local / abdominal lymph nodes.
- There are no hepatic parenchymal / bony metastases.
Incidental findings:
- There are two subcentimetric, hypodense, non-enhancing lesions in the liver, representing simple cysts.
The findings represent a neoplastic, multi-locular mass of mixed fluid and solid components arising from the pancreas.
Principal diagnosis:
Macrocystic mucinous cystadenoma of the pancreas.
Differential diagnosis:
- Mucinous cystadenocarcinoma of the pancreas
- Pancreatic pseudocyst (however, there is no history of prior pancreatitis)
- Serous cystadenoma (this usually has a different appearance with microcysts)
Management:
Alert referring physician of findings.
Refer for discussion at hepatobiliary MDT regarding further management / amenability for resection.
Case 4 Your Answer:
Case 5
Case 5 Model Answer:
Findings and interpretation:
- There is white matter FLAIR and T2 hyperintensity in the periventricular and deep white matter, centrum semi-ovale, and right parieto-occipital white matter; it is confluent in some areas and is more focal in others. Within this are small focal CSF signal lesions.
- There are 3 FLAIR and T2 hyperintense foci in the left temporo-occipital white matter, appearing bright on the diffusion weighted images, with corresponding low ADC values indicating diffusion restriction.
- There is parenchymal atrophy in the right parieto-occipital lobe with consequent dilatation of the occipital horn of the right lateral ventricle, indicating encephalomalacia resulting from chronic ischemic changes.
- The TOF images show severe stenosis alternating with non-visualization of both internal carotid arteries and the anterior circle of Willis. There are multiple small collateral vessels supplying the ACA and MCA on both sides. The right PCA shows severe stenosis and segments of occlusion, while the left PCA shows a few focal stenoses.
The findings represent acute lacunar infarcts in the left temporo-occipital lobe, combined with multiple scattered old lacunar infarcts on a background of leuko-encephalopathy. This is caused by a cerebro-vascular occlusive disease with greater involvement of the anterior circulation, with extensive small collateral vessel formation to bypass the occlusions.
Principal diagnosis:
Moya Moya disease.
Differential diagnosis:
- Atherosclerosis and arteriolosclerosis causing ischaemic disease of the white matter and lacunar infarcts (however, this is typically seen in older patients; also, the degree of small vessel collateralisation is characteristic for Moya Moya disease).
- CNS vasculitis
- Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy (CADASIL)- however, this is a microvascular disease; therefore, the internal carotids and circle of Willis are typically spared.
Management:
Alert referring physician of acute findings for urgent acute lacunar infarct management.
Recommend discussion at neurovascular MDT.
Case 5 Your Answer:
Case 6
Case 6 Model Answer:
Chronic osteomyelitis
Findings and interpretation:
Radiographs:
- There is a lucent, slightly expansile lesion in the proximal ulnar metaphysis and extending into the epiphysis.
- The lesion is centred on the medulla and shows a wide zone of transition.
- It demonstrates erosion of and extension beyond the cortex. There is new bone formation surrounding the lesion.
- There is a thick, dense and solid appearing periosteal reaction surrounding the lesion.
MRI
- There high PD and low T1 signal within and expansion of the metaphysis of the ulna, causing destruction of the cortex with surrounding new bone formation. The high signal extends through the bone marrow to the mid-diaphysis of the ulna, indicating pronounced extension of marrow oedema.
- The high PD signal extends to the surrounding soft tissues and around the bone, indicating periosteal reaction and oedema in the surrounding tissues.
- The lesion within the ulnar metaphysis shows avid enhancement on the post contrast sequences.
- An adjacent enhancing lymph node is also detected.
Radiography performed after 1 year:
- There is inhomogeneous osteosclerosis and expansion of the ulnar diaphysis and metaphysis, as well as interspersed lucent areas within.
Pertinent negative findings:
- There is no pathological fracture.
- There is no soft tissue mass.
- No abscesses are detected.
The findings represent a moderately aggressive bony process which is mainly inflammatory; the solid periosteal reaction implies chronicity and healing. The follow up radiograph demonstrates the sequelae of chronic infection with bony hypertrophy and multiple sequestrations.
Principal diagnosis:
Acute followed by chronic osteomyelitis.
Differential diagnosis:
- Eosinophilic granuloma (however, the follow up radiograph would not have that appearance)
- Ewing’s sarcoma (however, the follow up radiograph would not have that appearance)
Management:
Alert referring physician of findings.
Recommend discussion at paediatric orthopaedic MDT regarding further management.