Expansive processes in the musculoskeletal system refer to pathological changes that lead to an increase in volume or spatial pressure within bones, muscles, or other structures associated with the musculoskeletal system. These processes can be benign or malignant and include various types of tumors, cysts, or inflammatory changes. Tumors can also be primary (originating within bone/soft tissue) or secondary (metastatic). In this thesis, we will present the classification of bone and soft tissue tumors and describe some of their characteristics. Following this, we will describe the radiological methods used to image tumors of the musculoskeletal system. Radiological evaluation of musculoskeletal system tumors involves a multimodal approach, with each modality providing unique diagnostic insights. X-ray is the initial diagnostic method for assessing musculoskeletal system tumors, and the subsequent choice of radiological method is determined based on the X-ray image, the patient's medical history, physical examination findings, and the lesion's location. Following plain radiography, cross-sectional imaging techniques such as computed tomography (CT) or magnetic resonance imaging (MRI) are used. Additionally, nuclear medicine scintigraphy, ultrasound, and positron emission tomography (PET) can be utilized in conjunction with or following the initial evaluation. MRI is the preferred method for imaging soft tissue tumors, while both CT and MRI are used to assess the extent of bone tumors.