It is well-known in clinical practice that the manifestation of a pseudo-aneurysm as a musculoskeletal tumor is extremely rare. The peroneal artery aneurysm is usually diagnosed by physical examination and imaging. However, when a soft tissue aneurysm manifests with adjacent osseous changes, it can mimic a bone tumor or soft tissue sarcoma. In this study, we report a patient with pain and swelling in the shin in which aneurysm in peroneal artery has mimicked soft tissue sarcoma. This case is presented to emphasize that differential diagnosis is critical for pseudo-aneurysm and the appearance of a visible soft tissue mass or erosion in the adjacent bone.