Cyst-like lesion of the acetabular roof - an abnormal finding or an anatomical variant?

Cyst-like lesions are frequently found in the area of the acetabulum on MRI scans. However, their presence is not always abnormal. We report four patients with such lesions found on MRI where, during hip arthroscopy, an area resembling a horseshoe-like extension of the cotyloid fossa was found. Clinicians must be aware that not all cystic acetabular lesions are pathological and may simply represent a normal anatomical or developmental variant of the hip joint. They do not always represent an indication for hip arthroscopic surgery.