EN
The term “aggressive change” has been applied in radiology to describe pathological processes that are characterized by a violent and rapid development, connected with a very weak or even no reaction from the organism. Basic radiographic features that can decide whether the character of the process developing in bones is aggressive are: extraosseous extension/soft tissue mass, periosteal reaction, lesion margin, bone destruction, or rate of change. In this article the rules of interpretation concerning changes that have been noticed on the radiograph have been presented, without delving into the details of establishing the diagnosis of diseases. The degree of aggressiveness of individual radiographic features of abnormal bone tissue can occur differently. They should always be taken into consideration together. Yet those features which indicate a more aggressive character of the pathological process are deigned to be more important.