f/u 21F tibial lesion OFD vs Adamantinoma

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I was and remain confused about the specific imaging criteria to
distinguish osteofibrous dysplasia from adamantinoma.
If she were a child I would feel more comfortable reporting OFD…but she
is in this grey zone of young adulthood….and I don’t know if that has any
bearing on the diagnosis.
There is some erosion of hte outer cortex, though I don’t really see a soft
tissue mass.
The intracortical lesion avidly enhances, for what it’s worth.
The white arrow points to stress reaction along the posterolateral tibial
shaft, which might have brought her to urgent care and imaging in the first
place (though I don’t know for sure).

The comments ran the gamut.
Some thought the age favored adamantinoma or an intermediate grade OFD/LA
(“osteofibrous dysplasia like-adamantinoma”) lesion and warranted biopsy.
Others said simply “osteofibrous dysplasia, don’t touch”

This case was a consult for my colleague, referred by a DO in the community.
He decided to recommend orthopedic oncologic consultation so that someone
with more expertise would make the decisions and she would not fall through
the cracks.
If we can get biopsy f/u, I will share—-TBD.

A few people shared similar cases of young adults, skeletally mature
between 16-25, who were biopsy proven OFD. Those were among the people who
said “OFD”….though their cases were biopsied.
It seems reasonable to either biopsy or follow….but I still am unclear
what to recommend in terms of a regimen for follow up imaging surveillance.
It’s not clear to me, based on comments and email exchanges that anyone
knows (feel free to respond here with some clear guidance!)

*I’m sharing Mark Murphey’s comments*:
I look for the following for OFD (presentation before age 15 or so,
homogeneity on MR without intense areas of enhancement, no ST mass and
limited to no significant marrow encroachment). For Adamantinoma
[presentation after age 25 or so, heterogeneity on MR with areas of intense
enhancement (remember former name was angioblastoma), any ST component
(absolutely excludes OFD and seen in 15%-30% of adamantinomas),
encroachment on medullary canal). This comes from a series 20-40 of these
we looked at quite a few years ago and presented at SSR, as I recall. Can
send abstract, if you are interested and I can find it, to you next week as
I am working clinically until Tuesday.

In this case I would overall favor OFD. The age of presentation is
problematic because what you do not know is when the lesion began, for all
we know it was there when the patient was 5. All tumors have bell shaped
curves as far as age of presentation and outliers at the curve shoulders by
age make it difficult to hang your hat on that characteristic in an
individual case. The intense areas of enhancement make me a little nervous.
However, the degree of enhancement is always a little difficult to
quantitate and in the eye of the beholder. Was it uniform in degree of
enhancement throughout?

I do not think there is any correct answer here as far as follow-up. If
this were me or a family member, I would follow it up but that would be
over many years, particularly as there are some who believe the two lesions
may be related. If the symptoms go away as you suggest and are related to
stress related changes that would be helpful. Can do biopsy but not that
easy here and would create a stress riser. If biopsy, must tell pathologist
to do keratin stains and look for epithelial nests not just individual
positive cells.

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