This case illustrates an histologically proven sacrococcygeal chordoma. 

Chordomas are destructive bone tumors with large soft tissue component. Their distribution follow: Sacrococcygeal > spheno-occipital > mobile spine. Usually they are presented with an hyperintense T2WI signal, with multiple septa. They show normal or decreased uptake on bone scan

Differential diagnoses include:

• giant cell tumor
• chondrosarcoma
• metastases
• plasmacytoma