Presentation of Ewing’s sarcoma as unilateral sacroiliitis

Presence of sacroiliitis (SI) is one of the hallmarks for diagnosing seronegative spondyloarthropathy, especially ankylosing spondylitis. In certain cases, the occurrence of erosions around sacroiliac joint due to other causes can mislead the diagnosis. We are discussing here a rare case of Ewing’s sarcoma, which clinically presented as SI.