33-year-old male with history of treated Ewing's sarcoma. Currently off therapy for 1.5 years, assess for recurrent disease. Again seen is a pelvic mass located between the bladder and rectosigmoid colon, measuring approximately 6.2 x 5.5 cm in transverse dimension (series 601, image 23) and 5.7 cm in craniocaudal dimension (series 401, image 22), not significantly changed since the prior study. This mass demonstrates predominantly increased signal intensity on T1- and T2-weighted images, with a low signal intensity rim and no enhancement on post-contrast images. The MRI appearance is compatible with blood products of a chronic hematoma. Mild mass effect on the adjacent rectosigmoid colon is unchanged. The remaining visualized soft tissues are normal.An irregular enhancing region of signal abnormality in the anterior aspect of the left sacroiliac wing appears similar to the prior study and likely represents a small focus of bone infarction.Also redemonstrated is a small round non-enhancing focus of decreased signal intensity on T1-weighted images in the posterior aspect of the left iliac wing. While nonspecific, this could represent a treated metastasis.Patchy intermediate signal intensity within the vertebrae, pelvis, and proximal femora likely represents residual red marrow and is unchanged. Bone marrow signal intensity is otherwise within normal limits.
Post-treatment changes of pelvic Ewing's sarcoma, which appear similar to the prior study. No evidence of disease progression.