Musculoskeletal #22

What do you see?

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Vertebral hemangioma with thickened trabeculae and fat foci inside the lesion, without soft tissue component with an associated pathological fracture.

TEACHING POINTS:
Bone hemangiomas are very frequent, atypical presentations and complications (like in this cases with soft tissue component and pathological fracture) are rare but radiologist must be aware of them to be able to make the correct diagnosis.

Emergency #27 – Flashcard

Elbow pain after a fall. What do you see?

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Findings

Large joint effusion with the displacement of the anterior fat pad. Mild posterior soft tissue swelling over the olecranon. Fracture line along the lateral aspect of the radial neck. Radial head and articular surface are normal

Diagnosis

Nondisplaced radial head fracture

Teaching points

– Check not only the bones and joints but also the soft tissues
– Search and interpret the findings in two different positions
– Pain always withholds a story behind

Musculoskeletal #17 – Long Case

2-year-old girl, referring to emergency department after a fall.

What do you see?

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– An expansile lytic lesion with ill-defined margins (green arrow) is seen on the diaphysis of fibula.

– Lamellated periosteal reaction (red arrow) suggests an aggressive lesion.

Differential diagnosis of an aggressive lytic lesion in a 2-year-old child includes:
– Osteomyelitis
– Ewing’s sarcoma
– Langerhans cell histiocytosis
– Leukemia/lymphoma

What should be done next?

An MRI scan

Intramedullary hyperintense lesion with extensive surrounding soft tissue and bone marrow edema on coronal STIR image (a) is seen. The lesion is hypointense on T1 WI (b).

Cortical destruction is shown on axial PD image (arrow in c).

Postcontrast coronal (a) and axial fat-suppressed (b) T1-weighted images show extensive enhancement in the lesion and the surrounding soft tissue

Histopathologic examination revealed Langerhans cell histiocytosis.

Langerhans Cell Histiocytosis (LCH)

– LCH is characterised by idiopathic infiltration and accumulation of abnormal histiocytes within various tissues.

– Bone is the most commonly affected tissue in children, with a predilection for axial bones, and femur is the most commonly affected long bone.

– Radiographic appearance of the lesions depends on the site of involvement and the phase of the disease.

Skull: Calvarium is more affected than the skull base, typically seen as single or multiple well-defined lytic lesions on radiography; T1 hypointense, T2 hyperintense with significant enhancement on MRI. Temporal bone is the most common affected part of skull base seen as destructive lesions with a soft tissue component.
Spine: Vertebral bodies are affected with relative sparing of posterior elements. A typical vertebra plana appearance may be encountered with total collapse.
Long bones: Ill-defined lytic lesions with/without cortical destruction are seen usually located at diaphysis or metaphysis. Periosteal reaction may be present. Extensive bone marrow and soft tissue signal changes on MRI may also be helpful in the diagnosis.

Musculoskeletal #11

68-year-old male:
* Presents with a mass around knee which has been present for seven years and has been enlarging since then

What do you see?

A sclerotic ill-defined soft tissue mass around the knee was present on radiographs.
The mass is located in the soft tissue around the knee with no apparent bone destruction.

Coronal fat-suppressed T2 WI (a) shows a hyperintense lobulated mass which was hypointense on T1 WI (b) and has peripheral heterogeneous enhancement on postcontrast T1 WI (c); cortical bone is preserved.

The mass encircles a pedunculated lesion which continues with cortical and medullary bone (arrows), consistent with an osteochondroma.
Histopathologic diagnosis of the mass is chondrosarcoma.

Osteochondromas

* Osteochondromas are developmental lesions rather than true neoplasms and are often referred to as an osteocartilaginous exostosis (or simply exostosis).
* An osteochondroma is composed of cortical and medullary bone protruding from and continuous with the underlying bone; cortical and medullary continuity between the osteochondroma and parent bone is well depicted on MRI.
* Malignant transformation, almost invariably due to chondrosarcoma arising in the cartilage cap of the lesion, occurs in approximately 1% of solitary osteochondromas.
* Lesions that grow or cause pain after skeletal maturity should be suspected of malignant transformation since osteochondromas only rarely enlarge after this time.

Musculoskeletal #10 – Flashcard

29-year-old long-distance athlete presenting with 3 weeks of sciatica associated with an increase of running training loads

What do you see?

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IMAGING FINDINGS:

Unilateral sacral bone edema T2W, STIR hyperintensity associated with hypointense fracture line

DIAGNOSIS:

Fatigue stress fracture

TEACHING POINTS:

The sacrum is a frequent site for stress fractures
They can be related to overload occurring in a healthy bone as in this case, or related to osteoporosis (insufficiency stress fractures) in which cases they tend to be bilateral and “h- shaped”