[Male, 33 years old. Reason: Ewing's Sarcoma off therapy; completed chemotherapy and radiation therapy] [Again seen is a mass situated between the bladder and the rectosigmoid colon, measuring approximately 6.2 x 5.5 cm in transverse dimension (series 8, image 21) and approximately 5.9 cm in craniocaudal dimension, similar to the prior study. It is predominantly of increased signal intensity on T1 and T2 images with a low intensity rim and no enhancement on contrast images, with the MRI appearance a chronic hematoma. Mild mass effect on the adjacent rectosigmoid colon is unchanged.Mildly enhancing signal abnormality within the anterior aspect of the left sacral wing appears slightly less prominent on the current study than on the prior study and may represent a small focus of bone infarction from prior radiation therapy. An additional small round focus of decreased signal intensity best seen on T1 images in the posterior aspect of the left iliac wing is nonspecific and could represent a treated metastasis. The remaining visualized bones and soft tissues appear normal. The hip joints and sacroiliac joints appear normal.]
[Posttreatment changes of pelvic Ewing's sarcoma appearing similar to the prior study. We see no evidence of disease progression.