Musculoskeletal #12 – Flashcard

43-year-old healthy patient:
– with fibromyalgia
– No other relevant medical history

What do you see on the following images?

Click here to see the answer

IMAGING FINDINGS:

Multiple focal sclerotic bone lesions clustered around joints in both knees and sacroiliac joints

DIAGNOSIS:

Osteopoikilosis

TEACHING POINTS:

Sclerosing bony dysplasia characterized by multiple enostoses
Typically clustered around joints, aligned parallel to trabeculae. Usually 1-3 mm, they can reach up to 20 mm
Rare condition; inherited; asymptomatic; incidental
Important to avoid misdiagnosis with other relevant pathologies such as metastasis

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”

Musculoskeletal #9 – Flashcard

12-year-old boy, asymptomatic:

Radiograph a

Radiograph b

What do you see?

Lytic lesion on distal fibular metaphysis with well-defined sclerotic borders is seen on both anteroposterior (a) and oblique (b) radiographs

What do you see?

NOF: non ossifying fibroma

– Most common fibrous bone lesion
– Same as fibrous cortical defect but larger version
– If large enough, may cause pathological fractures
– One of DON’T TOUCH lesions

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