Imaging description

The radiographs may show focal cortical irregularities in the proximal humerus at various tendon insertion sites. Cortical thickening and lucency may be seen at the deltoid tuberosity (pseudotumor deltoideus) (Figure 18.1). Cortical irregularity may be seen at the anterolateral aspect of the proximal humerus corresponding to the pectoralis major tendon insertion site among gymnasts (ringman's shoulder lesion) (Figure 18.2). Similar radiographic findings may be seen in the proximal humerus anteromedially at the insertion site of the latissimus dorsi and teres major muscles. MR imaging shows signal changes in the corresponding cortex, tendon, and adjacent soft tissue and bone marrow.

Importance

Most of these cortical changes are explained by chronic or subacute avulsive injuries based on clinical history, imaging studies, and follow-up. When symptomatic, because of aggressive radiographic features, a malignant neoplastic lesion may be suspected and the focus may present as a pseudotumor.

Typical clinical scenario

Focal cortical irregularities of the proximal humerus may be asymptomatic, but may become a clinical issue when incidentally found. Symptomatic lesions affect both young and old patients, who usually present with chronic or subacute shoulder pain of insidious onset. History of vigorous exercise may be found in cases of chronic avulsive injuries in young patients. Physical examination may show tenderness to palpation and limited range of motion because of pain. The conditions may be confused with aggressive lesions such as infection and tumor. However, MR imaging is diagnostic for pseudotumor, avoiding biopsy and surgical intervention.