Soft tissue mass of the anterior upper arm

A man in his 30s presented with right anterior elbow pain after colliding with an opponent with his elbow in flexed position while playing basketball eight days previously. At the time of the collision he heard a pop. After the injury he noticed difficulty lifting heavy objects, turning a doorknob, opening bottles, or using a screwdriver, and he noticed a bulge on the arm. He did not seek medical care, however, because the pain began to improve. He reported no smoking or relevant medical history. He did not report any recent use of medications, including antibiotics and steroids. On clinical examination, there was no bruising. Right elbow flexion and forearm supination strength were reduced, while elbow extension and forearm pronation strength were preserved. He had a soft tissue mass at the proximal part of the anterior arm (fig 1). The Hook test and the Ruland biceps squeeze test were performed. The right distal biceps tendon could not be hooked during the hook test and his right forearm did not supinate by the Ruland biceps squeeze test. Fig 1