[en] We present a 2-year-old girl with an unusual presentation of Langerhans' cell histiocytosis (LCH). Five months prior to admission to our hospital, she received IV steroids for bronchial obstruction. On admission, clinical signs of SVC obstruction were evident and a mediastinal mass was evident on the chest radiograph and MRI. Biopsy revealed fibrosing mediastinitis. Five months later, osteolysis was present on a skull radiograph. Surgical biopsy of the skull lesion revealed LCH. This case is unique because it demonstrates a rare initial manifestation of LCH that has not been previously reported. Furthermore, the primary, solitary mediastinal manifestation without calcifications was histologically interpreted as fibrosing mediastinitis, and the final diagnosis of LCH was only made after identifying the skull lesion. (orig.)