Metachronous eosinophilic granuloma of bone.

We present the case of a 4-year-old girl who developed a metachronous osseous lesion of the left distal femur five months after successful surgical treatment of an eosinophilic granuloma in the left proximal femur. After treatment of the second lesion with curettage, no further recurrence occurred during a follow-up interval of 17 months. Radiologists should be aware that additional eosinophilic granulomas of bone, occurring in up to four years after the initial diagnosis, should still be interpreted as a localized form of Langerhans'cell histiocytosis with a more favorable prognosis than the multifocal disseminated form, with involvement of organ systems other than the skeletal system.