Histology and imaging of soft tissue sarcomas

Imaging and histology are two complementary morphological techniques which play a fundamental role in the diagnosis and management of soft tissue sarcomas. Imaging allows to identify some pseudosarcomatous benign lesions such as myositis ossificans, intramuscular hemangioma, angiomyolipoma, intramuscular lipoma, giant cell tumour of tendon sheath, desmoid tumour and elastofibroma. There is no formal criterion for diagnosing a sarcoma on magnetic resonance imaging (MRI) but malignancy is strongly suspected with the presence of necrosis and vascular, bone or joint invasion. Imaging may also suggest some histological types of sarcoma such as well-differentiated liposarcoma, dedifferentiated liposarcoma, synovial sarcoma or extraskeletal osteosarcoma. Imaging is also extremely helpful in determining the appropriate kind of sampling to carry out and in guiding the performance of a microbiopsy. The appearance observed on imaging should always be taken into consideration for the interpretation of the microbiopsy by the pathologist.