Chronic expanding hematoma might be a potential insidious challenge for orthopedic surgeon.

Chronic expanding hematomas can cause alarm both to the physician and to the patient because they simulate the growth of a malignant tumor. It is not always possible to bring back the cause to a specific traumatic event that the patient can remember. At this purpose, it is important to have a precise diagnosis when dealing with a growing mass and to exclude any malignancy before processing any treatment. In this article, we report the case of a young patient admitted to our department with a suspected soft tissue sarcoma, but imaging study and histological examination revealed to be hematoma. The authors want to emphasize the necessity of performing a complete clinical and instrumental study when surgeon has to deal with a growing mass. From accurate analysis of imaging, it is often possible to discriminate between malignancy and other benign forms.