Sacral insufficiency fracture after pelvic radiotherapy: a diagnostic challenge for a radiologist.

Sacral insufficiency fractures can occur as a complication after pelvic radiotherapy. Despite several recent studies showing high incidence of sacral insufficiency fractures in elderly women after pelvic radiotherapy this condition still remains underdiagnosed. We present a case of sudden onset of low back pain in a female patient with a history of cervical cancer radiotherapy. Initial diagnostic imaging misinterpreted SIF for metastasis. Bone scan and single-photon emission-computed tomography with low-dose computed tomography revealed the correct diagnosis. Due to the reasons that sacral insufficiency fractures still remain underdiagnosed this report is important to practical routine work of oncologists and radiologists.