9-year-old female with Langerhan's cell histiocytosis involving the pelvis. PELVIS:A heterogeneous, enhancing lesion is again identified within the right iliac wing. The lesion has further decreased in size since prior study and measures up to 0.8 x 1.4 x 1.8 cm (series 1001/17 and series 1101/15) on postcontrast images, previously 0.8 x 2.2 x 2.4 cm. Previously seen cortical involvement associated with this lesion appears decreased as well. No new enhancing lesions are identified to suggest additional sites of disease. Slight high signal of the left anterior superior iliac spine is most likely related to the normal physis.
Interval decrease in size of the right iliac wing lesion, consistent with treatment response. No new sites of disease.