Hi everyone,
Ran across a case today that has me stumped. Patient is a 20 year old woman with bilateral knee pain, worst in the MR imaged left leg, of sudden onset approximately one month ago. Pain is intermittent, but when there is a "flare", the patient reports not being able to walk. Conservative management has provided minimal, if any, relief. There are no signs or symptoms of infection.
Radiographs show an eccentric lucent lesion within the metadiaphysis of the distal left femur with involves and expands the posterolateral cortex. There is an additional lesion in the proximal right tibia that looks like a healed NOF.
On MR, the lesion is eccentric and partially within the marrow and partially involving and expanding the cortex. I favor this to also be NOF, but the thing that gives me pause is the amount of perilesional edema-like marrow signal. Infection is a top differential to me for that reason, or some other fibrous or fibroosseous lesion. A recent paper in Skeletal Radiology by Farooq and Belair (thank you Mario Moreno for the find) noted edema-like marrow signal associated with NOF can be seen and may represent active healing and/or involutional change of this "do not touch" lesion.
Does this look like an actively healing NOF? Would you follow it? Or do I forgo the do not touch mantra and recommend biopsy?
Thank you so much,
Jim Smith
Assistant Professor, Musculoskeletal Imaging
Department of Radiology and Imaging Sciences
Emory University
Farooq M, Belair JA. Edema-like marrow signal intensity (ELMSI) associated with nonossifying fibroma (NOF) on MRI: an uncommon finding in a common bone lesion. Skeletal Radiol. 2023 Mar 3. doi: 10.1007/s00256-023-04312-9. Epub ahead of print. PMID: 36867220.
