Hi Linh,
Nice pictures,
I am not worried about this appearance,
I think the hypo echoic area is simply some fat,
Nothing to worry about and nothing pathological,
Tears of the deep lateral rotators in my opinion are rare and without a history of trauma in a patient of this demographic it makes no sense,
I think it is fat in the potential space adjacent to the sciatic nerve.
Normal.
The G-min and G-med tendinosis and associated bursopathy is a likely cause for the symptoms.
Steve.