Hypermobile coccyx syndrome.

A 40-year-old woman referred to the radiology department because of pain in the region of the coccyx. There was no abnormality neither localized tenderness or swelling in the sacrococcygeal region. She had difficulty in defecation but gastrointestinal pathology such as stool test for occult blood was negative. For radiological examination lateral and postero-anterior X-rays and MRI studies were obtained. On the X-rays the distal part of the coccyx was not very clear. It was impossible to make any diagnosis especially in the distal coccygeal area but MRI study showed abnormally invard curve in the distal part of the coccyx (arrow) with iliococcygeal part of the levator ani muscle and precoccygeal soft tissue edema (curved arrow) (A, B).