Figure 2

A representative case of an 11-year-old girl with a pathologically-confirmed LCH lesion in the right iliac bone. (a) Coronal STIR image from the WB-MRI (left), trunk and lower extremity images of skeletal survey (middle), and anterior view of bone scan (right), obtained for the initial evaluation of the extent of the disease, are shown. A known LCH lesion was detected on WB-MRI and bone scan (dashed arrows), but not on the skeletal survey, probably because of overlying bowel contents. WB-MRI also revealed heterogenous signal intensity with a tiny cystic portion in a slightly enlarged thymus (solid arrow), which was well-visualized on the sagittal STIR image (b), suggesting thymic involvement of LCH. However, thymic involvement could not be detected on the skeletal survey or bone scan. (c) PET-CT scan showing heterogenous increased FDG uptake in the thymus (arrow), raising the possibility of thymic involvement of LCH. (d,e) Follow-up WB-MRI after 6 months of treatment showing decreased size of the lesion in the right iliac bone (dashed arrow, d), and the near-normalized size and signal intensity of the thymus (arrow, e). On the risk stratifications, the patient was under-classified as single system LCH without multiple bone lesions or CNS risk lesions on the skeletal survey and bone scan, but correctly classified as multisystem LCH without risk organ involvement on WB-MRI.