There is an intra-capsular lipomatous mass that looks uniformly dark on fat sat, but has dark linear internal stranding on T1,,,looks smooth and macrolobulated
Shape and extent best delineated in Radial series…looks smooth
Obl Axial demonstrate both synovitis and intracapsular lipomatous mass
I don’t see many primary intra-articular lipomas
Given the severity of the DJD, I wonder if this is a "secondary lipoma" aka Lipoma Arborescens
I found a reference that describes "diffuse villous", focal nodular frond-like and mixed forms of lipoma arborescens.
While this is focal nodular, it is smooth and doesn’t seem frond-like to me…..look at the case in the open access article.
Of course it’s purely academic, but I’d like to know, what do you think?
Hilary
The comments covered the spectrum….though Lipoma Arborescens was favored.
1 favored true intra articular lipoma
1 cautioned me that she reported a similar case that was a proven intra-articular ossicle; this was our original question before I posted the case.
It can be a difficult DDx…but I thought that the dark T1 internal septae looked typical of lipoma and would not be expected in a degenerative ossicle
I particularly liked a response from Marcelo Bordalo:
I believe in the hypothesis of a lipoma arborescens, considering the severe degenerative changes in the joint. Why does it look nodular? Maybe because the hip is a more constrained joint compared to the knee.
Of course this is just an academic question and will not affect management
This hip is destined for THR
Thanks to everyone who commented