A giant synovial cyst incidentally found in the right hip of a 67-year-old woman during a routine computed tomography scan in the follow-up of a colorectal cancer in complete remission. For better characterization of the lesion, MRI was performed. Sagittal PD-WI shows a smooth, large multiloculated cyst, communicating with the joint space through a stalk (arrow). The lesion, probably corresponding to an enlarged iliopsoas bursa, displaces anteromedialy the iliopsoas muscle, and despite its close contact with the iliac bone, any erosion is seen. Ip, iliopsoas; IB, iliac bone