Musculoskeletal #8 – Flash card

What do you see on the following images?

CT scout view

CT soft tissue window

CT bone window

Click here to see the answer

Skull eosinophilic granuloma
Well defined lytic lesion with scalloped edges. It involves both the inner and outer table. Narrow zone of transition, no cortical breakthrough and no soft tissue component.

Musculoskeletal #7 – Long case

10-year-old male:

Axial CT brain bone windows

Non-enhanced axial CT brain soft tissue window

Where is the lesion?

Occipital bone within the medullary cavity

What is it like?

Moth-eaten destructive permeative lytic lesion with wide zone of transition.  There is cortical disruption of both the inner and outer table of the skull and a large soft tissue component.

An MRI is performed.
Axial T1Weighted

Axial T2Weighted
Axial Gadolinium enhanced T1Weighted
What does the MRI show?

Destructive bone lesion with a large soft tissue component which is low signal intensity on T1, heterogenous intermediate signal on T2, and heterogeneous intense enhancement in the post contrast image. It causes mass effect on the adjacent brain parenchyma with no gross invasion.

What is the differential diagnosis?

Given the age of the patient the differential diagnosis includes:

* Osteosarcoma: most common primary bone tumor in young adults. Usually involves the metaphyseal regions of long bones but can occur at other sites. Aggressive lesion with sunburst periosteal reaction and calcified osteoid matrix. 

* Ewing's sarcoma: second most common childhood bone tumor. Typically an aggressive permeative tumor which arises within the medullary cavity of the bone and has a large soft tissue component. 

* Metastasis.

What is the most likely diagnosis?

Ewing’s sarcoma

Musculoskeletal #6 – Flashcard

28 year-old male with a history of shoulder dislocation.

Regarding this image:

What do you see?

Hill-Sachs lesion
* Edema on posterolateral humeral head secondary to compression fracture, well-demonstrated on axial fat suppressed proton density Weighted image
* Secondary to anterior dislocation of shoulder

Regarding this image:

What do you see?

Bankart lesion
* Tear/injury of anteroinferior labrum, well-demonstrated on axial fat suppressed proton density Weighted image
* Secondary to anterior dislocation of shoulder
* May have associated bony component

Musculoskeletal #4 – Long case

Regarding the following X-Ray:

Frontal x-ray of the right hand

Where is the lesion?

Metaphysis of the base of the fourth middle phalanx.

What are the radiological characteristics/findings?

Expansile lytic lesion (bubbly appearance) with narrow zone of transition, no cortical break through, and no soft-tissue component.

What is the differential diagnosis?

Enchondroma: Enchondromas have variable imaging appearances but are typically lytic lesions with non-aggressive features. They could show chondroid calcifications (rings and arcs calcification). But in the hands and feet they are typically purely lytic with no matrix.
Eosinophilic granuloma: It mainly involves the diaphysis and does not cross the growth plates. It appears as punched out lytic lesions without sclerotic rim.  Imaging appearance in the long bones depends on the phase of the disease which is imaged. It can look aggressive in the initial phase. In the healing phase it can show solid benign periosteal reaction.
Fibrous dysplasia.Usually shows ground-glass matrix but may be completely lucent or sclerotic. Well-circumscribed lesions with no periosteal reaction may lead to premature fusion of growth plates leading to short stature in the lower limbs and bowing deformities (Shepherd’s Crook deformity of the femoral neck)

What is the most likely diagnosis?

Diagnosis: Enchondroma

Regarding the diagnosis…

What are the associated syndromes with multiple enchondromas?

Ollier disease: multiple enchondromas are usually  confined to one side of the body and limited to the limbs. There is increased risk of chondrosarcoma 

Maffucci syndrome: multiple enchondromas with soft-tissue haemangiomas

Musculoskeletal #3 – Long case

Axial CT abdomen bone window

Axial CT abdomen soft tissue window

Where is the lesion?

Left iliac bone

What are the radiological characteristics/findings?

Large lytic lesion with wide zone of transition, cortical destruction, and large soft tissue component.
No specific matrix.

What is the differential diagnosis of an aggressive iliac bone lesion?

* Metastasis
* Plasmacytoma: solitary plasma cell tumor expansile lytic lesion with bone destruction and soft tissue component. Usually shows low signal intensity on T2 with variable post contrast enhancement. 
* Chondrosarcoma: malignant cartilage tumor destructive lytic lesion with intralesional rings and arcs calcification (chondroid matrix). High signal intensity on T2. 

What is the most likely diagnosis?

Plasmacytoma

Musculoskeletal #2 – Flashcard

13-year-old girl with knee pain for 2 months.

What do you see?

Click here to see the answer

Periphyseal (both knees) hyperintensity on sagittal fat suppressed T2 Weighted image (a) and Proton Density Weighted image (b) and hypointensity on sagittal T1Weighted image (c) (arrows).

FOPE: Focal periphyseal edema
– Mostly around the knees
– Both genders can be affected during skeletal maturation
– Painful manifestation of physiologic physeal fusion