Intramuscular hemangioma of the thoracic wall: Diagnostic challenge mimicking breast pathology—A case report

Intramuscular hemangiomas are uncommon benign vascular tumors, accounting for less than 1% of all hemangiomas, and are particularly rare in the thoracic wall. When originating from the pectoralis major muscle, they may clinically and radiologically mimic primary breast pathology, creating a diagnostic challenge. We describe the case of a 54-year-old woman undergoing routine breast imaging who presented with breast asymmetry, with the left breast being larger than the right, and a suspected left breast lesion on initial evaluation. Multimodal imaging assessment, including mammography, ultrasound, magnetic resonance imaging, and contrast-enhanced computed tomography, demonstrated a heterogeneous mass arising from the left pectoralis major muscle, clearly separated from the breast parenchyma, with imaging features consistent with an intramuscular hemangioma. Histopathological confirmation was not obtained due to patient refusal; however, the diagnosis was supported by characteristic findings on the multimodal imaging scan.