Osteitis Condensans Ilii.

Typical CT sclerotic changes of Osteitis Condensans Ilii. The sclerosis is continuous with the SIJ margin and particularly on the patient's right it has a triangular appearance.

There is also mild sclerosis in the right sacrum adjacent to the SIJ (Green arrow). Sclerosis of the sacrum can also be seen in OCI but its not as prominent as the ilum and doesn’t occur in isolation.

Important negative findings is preservation of the SIJ joint space and no erosions.