We would like to thank everyone for the amazing feedback we received on the thigh case we sent yesterday.
We had 34 replies, and everyone agreed that the main hypothesis is myositis ossificans / heterotopic ossification<radiopaedia.org/articles/heterotopic-ossification?lang=us>, and, considering that, suggested to do not biopsy, and perhaps use Xray for follow up.
I took the liberty to paste some of the answers below:
“MO, no differential….it is classic benign peripheral ossification. Don’t biopsy, it can be misinterpreted as sarcoma.”
“We used to use the name of “pseudomaliganant osseous tumor of soft tissue” to describe myositis ossificans with no history of trauma.”
“Looks like MO to me. Peripheral calcification rather than central as would be expected in Osteosarcoma. Any history of trauma? I’d probably follow with serial radiographs and if continued peripheral to central ossification pattern, then bx not needed .”
“Focal compression repetitive trauma ? Weight bar or cowbell —myositis ossification/heterotopic ossification. My humble opinion. No biopsy. False positive OS for pathologists.”
“I vote MO. Good location, lots of surrounding soft tissue edema, zonality and can enhance.”
“This looks good for injury with myositis ossificans. I suggest short interval follow up imaging, no biopsy. Curious to hear what others suggest and any follow up!”
“X-ray, MR, and CT are all very characteristic of myositis ossificans. Please do not biopsy it. The process is self-limited and no further testing is needed. If the patient wants some sort of reassurance you can just do a follow-up x-ray in 1-2 months.”
“I think it’s myositis ossificans given the peripheral ossification and soft tissue edema. Could get follow up X-rays to ensure expected maturation. Nice case.”
“For me, MO or organizing hematoma after muscle injury. No harm to wait a bit and see if this all cools down and continues to calcify. Biopsy specimen could be tricky for the pathologist; easy to overread.”
“Myositis ossificans. I would not biopsy and let this thing calm down. No history of direct trauma but this person does Crossfit so it’s trauma each workout”
“I favor MO given the peripheral zone of calcification and marked surrounding inflammatory reaction, and would advocate a repeat radiograph in a couple of weeks to show the maturation. You say no history of trauma but your pictures allude to a cross fit athlete, which is clearly a traumatic sport for the musculature. ”
“It looks like myositis ossificans especially given the degree of edema/inflammation. Also the zonal ossification supports this. Biopsy is not recommended as the results can look very aggressive like osteosarcoma. ”
Some friends suggested this literature:
radsource.us/myositis-ossificans/
www.ajronline.org/doi/pdf/10.2214/ajr.157.6.1950874
Thanks once again for your time and insight.
Best from Brazil,
Cordially,
Carlos Henrique M.F.Alencar, M.D.
OCAD-case-thigh-pain.pptx 
I have been planning to write up on HO for a long time. If anyone wants to join forces, it would be great. We can pool in the cases-
Here are the signs on MRI that should go in the literature:
Bright T1 signal
Internal hemorrhage on fst1
Dark hemosiderin and later dark calcific ring on T2W and susceptibility weighted imaging
Marbled (muscle like) appearance of the lesion
Extensive associated fascial edema
ADC>1.3
Early and persistent perfusion
Marbled or peripheral delayed enhancement
Best!
AC
Avneesh Chhabra, M.D. M.B.A.
Professor Radiology & Orthopedic Surgery
Chief, Division of Musculoskeletal Radiology
UT Southwestern Medical Center, Dallas, Tx
5373 Harry Hines Blvd.
Dallas, Tx-75390-9178
Office: 214-648-2122
avneesh.chhabra@utsouthwestern.edu<mailto:avneesh.chhabra@utsouthwestern.edu>
http://www.utsouthwestern.edu<http://www.utsouthwestern.edu/>
________________________________
Sent: Tuesday, March 8, 2022 7:00 PM
EXTERNAL MAIL
Hello, friends,
We would like to thank everyone for the amazing feedback we received on the thigh case we sent yesterday.
We had 34 replies, and everyone agreed that the main hypothesis is myositis ossificans / heterotopic ossification<radiopaedia.org/articles/heterotopic-ossification?lang=us>, and, considering that, suggested to do not biopsy, and perhaps use Xray for follow up.
I took the liberty to paste some of the answers below:
“MO, no differential….it is classic benign peripheral ossification. Don’t biopsy, it can be misinterpreted as sarcoma.”
“We used to use the name of “pseudomaliganant osseous tumor of soft tissue” to describe myositis ossificans with no history of trauma.”
“Looks like MO to me. Peripheral calcification rather than central as would be expected in Osteosarcoma. Any history of trauma? I’d probably follow with serial radiographs and if continued peripheral to central ossification pattern, then bx not needed .”
“Focal compression repetitive trauma ? Weight bar or cowbell —myositis ossification/heterotopic ossification. My humble opinion. No biopsy. False positive OS for pathologists.”
“I vote MO. Good location, lots of surrounding soft tissue edema, zonality and can enhance.”
“This looks good for injury with myositis ossificans. I suggest short interval follow up imaging, no biopsy. Curious to hear what others suggest and any follow up!”
“X-ray, MR, and CT are all very characteristic of myositis ossificans. Please do not biopsy it. The process is self-limited and no further testing is needed. If the patient wants some sort of reassurance you can just do a follow-up x-ray in 1-2 months.”
“I think it’s myositis ossificans given the peripheral ossification and soft tissue edema. Could get follow up X-rays to ensure expected maturation. Nice case.”
“For me, MO or organizing hematoma after muscle injury. No harm to wait a bit and see if this all cools down and continues to calcify. Biopsy specimen could be tricky for the pathologist; easy to overread.”
“Myositis ossificans. I would not biopsy and let this thing calm down. No history of direct trauma but this person does Crossfit so it’s trauma each workout”
“I favor MO given the peripheral zone of calcification and marked surrounding inflammatory reaction, and would advocate a repeat radiograph in a couple of weeks to show the maturation. You say no history of trauma but your pictures allude to a cross fit athlete, which is clearly a traumatic sport for the musculature. ”
“It looks like myositis ossificans especially given the degree of edema/inflammation. Also the zonal ossification supports this. Biopsy is not recommended as the results can look very aggressive like osteosarcoma. ”
Some friends suggested this literature:
radsource.us/myositis-ossificans/
http://www.ajronline.org/doi/pdf/10.2214/ajr.157.6.1950874
Thanks once again for your time and insight.
Best from Brazil,
Cordially,
Carlos Henrique M.F.Alencar, M.D.