Pseudotumor Deltoideus: Touch Me Not Lesion of the Humerus

Pseudotumor deltoideus is a localized region of irregular cortical thickening at the deltoid insertion that causes a diagnostic quandary for radiologists due to its unusual radiological characteristics. It is benign in origin, with the potential to act as a tumor stimulator, and has a variety of anatomic variants. The lesions can be characterized on an X-ray by an area of lucency at or around the deltoid tuberosity and a cortical irregularity or nearby eccentric marrow abnormality on computed tomography (CT)/magnetic resonance imaging (MRI). The presence of cortical thickening and lucency at the deltoid insertion are unusual radiological findings that provide a diagnostic challenge. In this article, we provide cases of shoulder pain together with radiological imaging to make this previously underappreciated condition more understandable. Further evaluation with CT/MRI should be performed in all cases of shoulder pain with conventional radiographic findings of cortical thickening and intracortical lucency. The diagnosis of the condition is aided by the presence of elongated lucency on CT and T2 hyperintensity in the cortex of the proximal humerus. The clinical and imaging characteristics are important in the diagnosis of this condition. It must not be confused for infection or malignancy, and a biopsy must never be attempted.