Radial nerve was traced from proximal arm to its bifurcation. Anterior branch was traced up to the wrist. Posterior branch was traced up to mid-forearm. Nerve could not be traced distally to this.
There is a well-defined, encapsulated lesion elevating proximal part of the posterior interosseous nerve meaning there is a lesion deep to the nerve. The lesion is solid, iso to hypoechoic to adjacent to muscles with linear internal strands. There is no calcification / cystic changes / vascularity in the lesion. Approximate size of the lesion is about 29 x 26 x 18 mm. With elbow flexion-extension, the lesion is deformable. Lesion the abutts part of the radial cortex.
The radial nerve is separate from the lesion. Lesion abutts proximal part of the anterior branch of radial nerve without displacing it. The posterior interosseous nerve is hypoechoic, thickened due to compression by this lesion. The nerve is affected from its origin to proximal forearm level. Radial nerve and anterior interosseous nerve show normal echo-pattern.
Extensor muscles in mid forearm show moderate diffuse fatty infiltration and mild volume loss as compared to asymptomatic left side.