A Case of Report of False Aneurysm of unknown Cause

False aneurysm is characterized by partial wall involvement, with partial tissues forming a false wall lined by endothelium.False aneurysms occur most commonly following penetrating trauma such as stab wounds.In this study, we report a case of false aneurysm of the right buttock. The patient was a 39-year-old man without a history penetrating trauma. An elastic hard mass was palable in his right buttock. MRI revealed a soft tissue mass deep to the gluteus maximus muscle. The image of the lesion was not compatible with typical findings of tumor. Histological examination from needle biopsy showed coagulative necrotic tissue.Surgical extirpation was performed. The mass was pulsatile, with a scroll-like blood flow observed inside the mass wall by ultrasonography.The case was diagnosed as a false aneurysm during surgery, and this diagnosis was confirmed by histological findings.