Case 147: Langerhans Cell Histiocytosis of the Femur

History A 12-year-old boy presented with pain in the right thigh that had persisted for 4 days. There was no trauma, and the patient's history provided no clues. The proximal thigh was tender on palpation, and there was no swelling or reddening. The patient's white blood cell count and other laboratory parameters were unremarkable. Conventional radiography and 3-T magnetic resonance (MR) imaging of the right femur were performed before and after administration of gadoterate meglumine (Dotarem; Guerbet, Paris, France). Open biopsy was performed 5 days after imaging to enable histologic confirmation.