Sacral chordoma, restaging Note that the examination is limited by motion artifact, particularly the pre and postcontrast sequences.There are surgical changes of a partial sacrectomy extending from the level of S2 down with displacement of the rectum posteriorly, appearing similar to the prior study. There is fluid signal surrounding the rectum, likely representing a small amount of physiologic free fluid which has decreased from the prior exam and is probably of no significance.Edema-type signal within the bodies of the pubic bones adjacent to the symphysis may be degenerative in etiology but is also less prominent on the current exam.Numerous nodular masses are again noted within the gluteus maximus musculature bilaterally as well as within the adjacent subcutaneous fat of the buttocks bilaterally. Additional nodular masses are situated along the posterior column of the acetabula adjacent to the obturator internus muscles, more so on the left than on the right. These masses are hypointense to skeletal muscle on T1 sequences and heterogeneously hyperintense to skeletal muscle on T2 sequences. Following contrast administration, they demonstrate heterogeneous enhancement. One of the larger masses within the left gluteus maximus muscle again measures approximately 6 cm obliquely on series 9, images 9 through 12. A second mass within the subcutaneous fat between the intergluteal cleft and the medial margin of the left gluteus maximus (series 6 image 29) measures approximately 2.8 x 1.8 cm, similar to the prior exam. A smaller mass within the medial fibers of the right gluteus medius muscle (series 8 image 23) measures approximately 2 x 1.4 cm also similar to the prior exam upon remeasurement (the previous measurement of this lesion [1.5 x 1 cm] is suspected to have been placed erroneously). Multiple additional lesions are seen which appear similar in size and extent to the prior exam and although the enhancement appears more prominent, this may be secondary to technical factors and the timing of contrast administration.
Multiple masses within the posterior soft tissues as described above, representing multifocal chordoma. When compared to the prior exam, overall these lesions appear similar in size and extent.