0:00

Next case and that was the question for it.

0:04

So, young female who presented with upper back pain...

0:13

Well, initially radiographs were done. They were red normal, she was sent

0:17

home but she kept coming back with back pain so eventually somebody decided

0:21

to do an MR. An MR showed the signal abnormality here along the

0:25

upper thoracic spine. You can see it here. This is your axial post

0:31

contrast. You can see the enhancement and sagittal post contrast, T1 weighted

0:40

images again, we can see the enhancement. So I can think of some

0:45

of the differentials for this lesion or the abnormality, what will you think

0:50

when you have sclerosis and enhancement involving the spine in a young patient?

0:56

And there were certain differentials that were entertained based on MR and

1:01

to confirm the diagnosis, a CT was performed,

1:07

and these are the CT images. And can we have the last question,

1:10

please? So, what will be the treatment of choice in this case?

1:13

Antibiotics, chemotherapy, surgical fixation, or resection and fixation?

1:19

Let's look at the answers. Resection and fixation, that's the correct answer

1:25

because this is an example of an osteoid osteoma involving the posterior

1:29

elements of the spine and this needs to be resected and then spinal

1:34

fixation needs to be done in these cases. So, the clue to the

1:37

diagnosis is, again, age is important. In a young patient, if you see

1:41

a whole lot of sclerosis, especially in the posterior elements of the spine,

1:45

and then surrounding edema and inflammation and soft tissue enhancement,

1:49

an important consideration is an osteoid osteoma. You often need a CT to

1:53

look at the nidus because often on MR, this nidus will be not

1:59

readily apparent because of limited spatial resolution and surrounding edema.

2:03

The nidus is very well seen on CT and here we see a

2:06

hyperintense nidus in the posterior elements of the spine so this was a

2:10

case of osteoid osteoma which was... This is a difficult location to do

2:15

an RFA so that's why it's just resected and fixed.

2:21

So, what's an osteoid osteoma? It's a benign bone tumor characterized by

2:24

central nidus that consists of osteoid osteoblasts and variable amount of

2:28

fibrovascular stroma and that is intensely vascular and that's why it causes

2:33

severe pain. And this nidus is sounded by dense, reactive bone so it

2:38

causes a lot of inflammation and in sites surrounding sclerosis, accounts

2:43

for 10% to 11% of all benign bone tumors, mostly in men and

2:47

boys between 10 to 25 years of age, and classically present with pain

2:52

that worsens at night and it's promptly relieved by administration of NSAIDs.

2:57

So, younger patients, they can be seen in long bones, metaphysis or diaphysis.

3:03

So femur neck is a good location, posterior elements of spine is good

3:06

location. They're often intracortical, though. They rarely can be intramedullary

3:11

subperiosteal but they're often intracortical and the imaging hallmark is

3:15

to look for the central nidus surrounding by the dense, sclerotic bone.

3:20

And again, on cross section imaging, you'll see intense surrounding bone

3:23

and soft tissue edema. And CT is the imaging modality of choice to

3:28

demonstrate the nidus. Intraarticular osteoid osteomas are considered a

3:33

separate clinical entity, most commonly involved joint is hip.

3:37

The difference in this is it incites less sclerosis around it so,

3:42

again, it gets harder to pick up such lesions but any time you

3:46

have a lot of synovial hypertrophy, joint effusion, extensive marrow edema,

3:50

again, in a younger patient who clinically doesn't present like septic arthritis,

3:54

again, we need to consider osteoid osteoma and it requires CT to demonstrate

3:58

that nidus. And some of the other uncommon locations listed here. The differentials

4:03

are going to be an intracortical abscess and as I said

4:07

earlier while trying to differentiate abscess from a chondroblastoma, in

4:11

an abscess, the inner side is irregular, whereas in a nidus, the inner margin

4:15

is smooth. Nidus has this central calcification from osteoid deposition

4:21

which is often central, whereas an abscess, if there is a chronic infection

4:25

and there is a sequestrum formation, that will also be seen as calcification

4:30

but it'll often be eccentrically located. The center of an abscess does

4:34

not enhance, whereas an osteoid osteoma, the central nidus enhances strongly

4:38

so that's an important differentiating point. And the cortical abnormality

4:43

can also mimic a stress fracture but these are often horizontally located

4:47

in the area of cortical thickening versus nidus is a round thing.

4:53

And chondroblastoma but chondroblastomas are usually epiphyseal and intramedullary,

4:58

whereas these are often intracortical and rarely epiphyseal. Treatment,

5:04

they may be self limiting, so they can just resolve on their own

5:08

but if the pain is severe, they can be put on NSAIDs.

5:12

They do frequency ablation as a treatment of choice for asymptomatic osteoid

5:17

osteomas, especially in the extremities, and sometimes if they are recurrent,

5:21

extensive, or involving the spine, will require excision. So, quickly a

5:26

few companion cases and we're almost done here, extending beyond time a

5:34

little bit. You have this nice lesion. Though it looks intramedullary here

5:38

but on the lateral, it's along the posterior cortex. You have a lucent nidus

5:42

with reactive sclerosis around it. And on MR, again, we see the same

5:48

findings. You have this nidus in the posterior cortex with marked surrounding

5:53

bone thickening and sclerosis and surrounding soft tissue edema. CT shows

5:59

this classic nidus with that central osteoid matrix, this hypodensity from

6:07

the fibrovascular core, and then surrounding bone thickening and sclerosis.

6:13

And when you ablate, we ablate this nidus so that the symptoms are

6:17

resolved. So that was all about osteoid osteoma. We have a last case here.

6:24

A young patient and there's no question associated with it so I'll just

6:28

describe it, here. We have a lytic lesion in the proximal metaphysis which

6:34

is eccentrically located. It has well circumscribed thick, sclerotic margins

6:39

and thick internal trabeculation and septation so this is

6:43

an antimony appearance for what is known as known as non ossifying fibroma

6:48

and on MR, these lesions typically look very T2 dark because of the

6:52

fibrous component in them. It's one of the most common bone lesion encountered

6:57

by radiologists. It's seen in 20% of the children and a lot of

7:03

them just spontaneously regress so these are like those, "Do Not Touch"

7:07

lesions where you see them, but you know that they are going to

7:10

spontaneously involute at one point or the other.

7:14

There's another term that is used, which is known as fibrous cortical defect.

7:17

It's used for lesions that are smaller than two centimeters but fibrous

7:21

cortical defect and non ossifying fibroma, histologically, are the same

7:27

entity. It's the size is the difference. Less than two centimeters,

7:30

you call them as FCD; More than two centimeters, you call them as

7:34

NOF. They are asymptomatic, occur in the metaphysis, eccentric along the

7:40

cortex. They have sclerotic margins and, as I said, these are "Do Not

7:44

Touch" lesions so we should make the right diagnosis and not recommend biopsy

7:48

or aggressive treatment for such patients. So we looked at top seven benign

7:53

bone tumors in today's case conference and I hope next time you see

7:57

them, you will be able to make an accurate diagnosis and know some

8:00

of the common differentials and how to troubleshoot those cases.

8:04

And I know we ran out of time, if there are any questions.

8:09

Thank you, all.