Recurrent Ewing sarcoma, restaging following adjuvant chemotherapy for relapse There has been significant interval reduction in size of the mixed solid and cystic mass previously noted to encase the left inferior pubic ramus. A discrete soft tissue component is not well seen with an estimated residual tumor in the area of less than 5 cm. Within the adductor musculature below the superior pubic ramus are pockets of fluid thought to represent areas of necrosis which are best appreciated on axial postcontrast images 12 and 14 of 44. Additionally, the focus of enhancement within the left ilium is again seen but has decreased in size suggesting response to therapy.There is redemonstration of decreased T1 signal within the proximal aspect of the right inferior pubic ramus. Additionally, there is decreased T1 signal throughout the left inferior pubic ramus. There is increased extent of low T1 signal within the left iliac wing which extends to the level of the SI joint. Patchy areas of low marrow signal are also seen in the proximal femora and sacrum which also appear more conspicuous on the current exam.There is redemonstration of postsurgical changes relating to prior resection of the right iliac bone with associated superior migration and flattening of the femoral head. There is an old surgical tract through the femoral head.There is similar high T2 signal and enhancement within the pubic/adductor musculature, likely reactive in nature. There is generalized atrophy of the muscle on the right.At the request of the clinical service, the current study was briefly compared to a outside MRI study from March 11, 2016. The left pubic mass and suspected metastatic foci appear slightly smaller on the current study than on this prior outside study as well.
1. Significant interval reduction in size and extent of pelvic recurrence particularly surrounding the left inferior pubic ramus. Small amount of residual necrosis is evident.2. Patchy areas of intermediate and low marrow signal throughout the pelvis, femora, and lower spine. This are thought to be posttreatment-related with progression of disease thought to be less likely given the findings above.3. Additional chronic findings described above.