Synovial sarcoma from imaging to immunohistochemistry

The recent World Health Organization classification of soft tissue tumors 2020 has categorized tumors into 11 subtypes based on histopathology, immunohistochemistry, and molecular genetics. A radiologist must be well-versed with the current classification to characterize the tumor with some certainty, apart from staging, and determining recurrence, residual, and response to treatment on imaging. Synovial sarcoma is a malignant soft tissue tumor that commonly affects teenagers and young adults between 15 and 40 years of age. Here, we present a case of a woman in her late 20s who had pain and swelling in her right elbow for 1 year. Magnetic resonance imaging revealed a multi-lobulated soft tissue mass in the proximal meta-diaphyseal region of the right radius and ulna with numerous cystic and necrotic areas. The mass extended into the medulla with cortical erosion of the bone underneath. Histopathology showed spindle-shaped cells that were positive for transducin-like enhancer split immuno-stain.