Erdheim-Chester disease in a child with MR imaging showing regression of marrow changes

Objective Erdheim-Chester disease is a disseminated xanthogranulomatous infiltrative disease of unknown origin that generally presents in adulthood. A review of the English-language literature demonstrated that pediatric cases were extremely rare, and to our knowledge, only two cases, a 7- and 14-year-old, have been published. Design and patient We report a case of Erdheim-Chester disease in a 10-year-old girl evaluated with MR imaging. Radiographs revealed typical bilateral, symmetric osteosclerosis of the metaphyseal regions of long bones of the upper and lower extremities. Results A histologic examination demonstrated foamy histiocytes in bone marrow smears. Bilateral symmetric low signal intensities of both proximal tibiae and distal femurs were demonstrated on T1-weighted MR images. After oral steroid therapy for 8 months, follow-up MR imaging showed remarkable restoration of normal high signal intensity in both the tibial and femoral metaphyses. Conclusion To our knowledge, this may be the first case of Erdheim-Chester disease that showed normal restoration of the abnormal signal intensities in the metaphyses of long bones after steroid therapy.