Hi Ray,
Great case and awesome images as always from you,
I have never seen a tear of the lateral fibres of iliacus so I am suspicious about this diagnosis,
I wonder if you are seeing a paralabral cyst from an anterior labral tear,
I think this is more likely as I have not seen a lateral fiber of iliacus tear before.
Also, was there a history of trauma?
If the answer is no, I would be thinking para-labral cyst for sure.
The paralabral cyst can certainly work its way through the joint capsule and end up in this location.
An MRI would settle the argument.,
Another aspect is that the area of concern is nice clean cystic areas with no other apparent damage to the lateral fibers of iliacus muscle.
On balance I am going for a paralabral cyst rather than a primary muscle tear.
Do the MRI and see if I am wrong !!!!
Steve