Presentation
Focal swelling at the distal left arm. There was no pain or tenderness.
Patient Data
Cortical thickening in the proximal humerus deltoid insertion is accompanied by intracortical lucency. An intramuscular lucent lesion is also seen adjacent to the distal third of the humerus, suggestive of lipoma (confirmed with ultrasound).
Cortical thickening in the proximal humerus deltoid insertion is accompanied by intracortical lucency. The yellow arrow shows an intramuscular lucent lesion adjacent to the distal third of the humerus, suggesting lipoma. (Lipoma is confirmed with ultrasound at the site of swelling pointed by the patient.)
Case Discussion
Pseudotumor deltoideus (prominent deltoid muscle insertion) is an anatomical variant that can be confused with bone neoplasms. Complaints and radiographic changes in this location may lead to misdiagnosis by those unfamiliar with this anatomical variant. Well-defined borders and the typical location on the lateral aspect of the humerus at the level of deltoid insertion can help make the diagnosis and differentiate it from a neoplasm.