Case report: Longitudinal stress fracture of the humerus: imaging features and pitfalls.

Longitudinal stress fractures are an uncommon injury in which a diaphyseal fracture line occurs parallel to the long axis of a bone in the absence of direct trauma. They have been described in the tibia and less commonly in the femur but apparently not in the upper limb. We report a longitudinal stress fracture occurring in the humerus of a 62-year-old woman who had a history of osteoporosis and had undergone recent surgery of the contralateral wrist. We present the radiographic, MRI, and CT features of the case and emphasize the difficulties in diagnosis caused by negative findings on early radiographs and by nonspecific bone marrow edema pattern on MRI. The risk of a contralateral upper extremity stress fracture from activities of daily living in a patient with osteoporosis whose other upper extremity is immobilized also is highlighted.