Various Tumor-Mimicking Lesions in the Musculoskeletal System: Causes and Diagnostic Approach

Tumor-mimicking lesions in the musculoskeletal system can be defined as lesions mistaken as tumors due to the presence of palpation upon physical examination or a tumor-like appearance upon radiological examination. Moreover, tumor-mimicking lesions show diverse etiologies and anatomic locations. We illustrated the various tumor-mimicking lesions involving bone and soft tissue. In this review, the tumor-mimicking lesions were classified into those based on clinical examination and those based on radiological examination in musculoskeletal radiology. Awareness of the various causes of tumor-mimicking lesions, correctly obtaining clinical information, and the proper selection of imaging modality are important for the differentiation of tumor-mimicking lesions from true neoplasms.

A Localized-type giant-cell Tumor of the Tendon Sheath Arising from the Deep Infrapatellar Bursa that Presented as a Palpable Mass Around the Knee

A giant-cell tumor of the tendon sheath (GCTT) predominantly affects the tendon sheaths or joints of the fingers and toes. Less common sites include large joints such as the ankle and knee joint. We describe a case of a 35-year-old female with a localized giant-cell tumor of the tendon sheath that uniquely originated from the deep infrapatellar bursa.

The Role of Fat Tissues in the Diagnosis of Musculoskeletal Imaging

Fat tissue is a unique component of the soft tissue, and this fat tissue lies primarily in the spaces beneath the normal subcutaneous tissue, and within or around the organs. An entire lesion, or just a part of it, can be composed of these fat tissues. Therefore, it plays an important role in the diagnostic workup of suspected musculoskeletal diseases as well as in the differentiation between them. Fat tissue is shown as low density on plain radiographs, decreased attenuation on CT images, high signal intensity on T1-weighted images and it is hypoechoic on sonography. Because of its distinctive features, fat tissue is easy to verify on various modalities.?In addition, recent image studies like fat-suppressed imaging and STIR imaging provide more precise information of the lesion that involve fat tissue. In this article, we have reviewed the differentiation of musculoskeletal diseases, including the various tumorous lesion and tumor-like lesions involving the fat tissue.