Synovial sarcoma (SS) is a rare malignant neoplasm of the soft tissue adjacent to joints. It is the most commonly diagnosed non-rhabdomyosarcoma soft-tissue sarcoma (STS) in childhood (30%). Its most frequent location is the knee and ankle, and it is the most common STS to affect the foot. Unlike other STS, it has slow growth and an earlier age at diagnosis (adolescents and young adults), which is why many cases are initially misdiagnosed as benign processes. Magnetic resonance imaging (MRI) is key due to its characterisation capabilities as SS shares features with other STS. Definitive diagnosis is achieved through a pathological study that shows the pathognomonic translocation t(x
18)(p11
q11) with the fluorescence in situ hybridisation (FISH) technique. The objective of this article is to highlight the key characteristics that are useful for diagnosing SS, fundamentally through the use of radiological imaging techniques, as well as nuclear medicine and pathological studies, illustrated with cases diagnosed in our centre.