Pseudotumor deltoideus: a previously undescribed anatomic variant at the deltoid insertion site

A spectrum of eccentric bone irregularities were observed in the humeral de ltoid tuberosity region of five patients. Patients were referred for associ ated pain or for the incidental radiographic findings. The lesions are char acterized radiographically by a relative lucency at or adjacent to the delt oid tuberosity, variably increased uptake on the bone scan, and mild cortic al irregularity or adjacent eccentric marrow abnormality on MRI and CT. The term pseudotumor deltoideus is coined for these previously undescribed ana tomic variants. Imaging studies and extended clinical follow-up in these pa tients support an inactive or indolent process that may be managed conserva tively. The potential etiology and role of these cortical irregularities as tumor simulators is emphasized.