‘Butterfly Sign’ In Bone Scan Leading To Diagnosis of Post Radiotherapy Sacral Insufficiency Fracture in a Case of Carcinoma Cervix

Sacral insufficiency fracture is a known complication after pelvic radiotherapy. The condition can be missed if clinical suspicion is not high er can be misdiagnosed as metastases. Imaging modalities play a vital role in correct diagnosis of this pathology. We describe intriguing ‘Butterfly sign’/’Honda sign’ in sacro-iliac region on bone scan in a patient of carcinoma cervix. Further clinical and radiological evaluation revealed presence of sacral insufficiency fracture. Temporal relation of pathology to radiotherapy suggested possible role of Radiotherapy resulting in SIF. SIF should be considered in differential diagnosis of post radiotherapy patients complaining of sacral pain.