Benign chordoma of the sacral bone. Radiologic appearance and differential dignosis

Chordomas constitute 3-4% of all primary bony tumors [17, 20] and they arise from remnants of the notochord [4]. They can occur anywhere along the skull base and spine, where the notochord extends. 50% arise in the sacrum, 35% in the clivus and 15% in the vertebrae [17, 20]. Chordomas usually occur after the second decade with the highest incidence between the fifth and seventh decade. There is a male predominance, with roughly a 2 to 1 male-to-female ratio. Children are rarely affected [5, 25, 34]. In this article a case of a patient with a Chordoma of the sacrum is presented. After a fall on the coccyx the patient complained of recurrent and altogether increasing pain for some years. The clinical diagnosis was fracture of the coccyx with consecutive formation of callus. Finally the MRI showed a characteristically increased signal intensity in the T2-weighted spin-echo sequence (SE). With the help of MRI guided biopsy the diagnosis of a benign highly differentiated chordoma could be confirmed. (orig.)