A 14-year-old has forearm pain after falling on an outstretched hand. What is the likely diagnosis based on a positive fat pad sign?

The likely diagnosis in this scenario, indicated by a positive fat pad sign, is a radial head fracture. The fat pad sign refers to the appearance of displaced fat pads on an X-ray, which typically occurs when there is an underlying fracture, particularly in the context of elbow injuries following trauma, such as falling on an outstretched hand.

In children, the radial head is one of the most common sites of fracture in such scenarios. The fall can lead to the dislocation of the elbow or a fracture of the radial head, resulting in injury to the surrounding joint structures and causing the characteristic fat pad sign.

Furthermore, this injury often presents with symptoms such as localized pain, swelling, and limited range of motion at the elbow, which further supports the diagnosis. The presence of the positive fat pad sign serves as an indication of intra-articular injury, honing in on the diagnosis of a radial head fracture as the most likely injury resulting from the fall.

Other options, such as an upper arm sprain, lateral epicondylitis, or olecranon bursitis, do not typically present with a fat pad sign on imaging. These conditions have distinct clinical presentations and affect different anatomical structures. For example, lateral epicondylitis commonly involves chronic over