Langerhans cell histiocytosis mimicking malignancy: A radiological appraisal

Aims: To analyze the radiologic characteristics, clinical course and long-term follow-up of 7 radiologically uncommon pediatric cases of Langerhans cell histiocytosis and to identify prognostic factors related to imaging patterns. Methods: The clinical records and complete imaging data of 75 patients with LCH diagnosed and treated at the National Cancer Institute of Milan between January 1975 and December 1993 were analyzed, and 43 cases presenting as unifocal bone lesions were identified. The plain film, computed tomography and magnetic resonance characteristics enabled the identification of 7 radiologically aggressive and rapidly progressive cases, which were analyzed at presentation and during follow-up. Results: Although at disease presentation bone lesions appeared lytic destructive, rapidly progressive and often involved adjacent soft tissues, after adequate therapy the disease course was invariably benign and led to almost complete restoration of normal structure and function. Long-term follow-up confirmed the favorable outcome and lack of disease recurrence in all cases. Conclusions: There is no correlation between radiologically aggressive characteristics and final outcome in Langerhans cell histiocytosis. Radiologists and pediatric oncologists should be acquainted with less common radiologic forms which, at presentation, can mimic more ominous diseases. If recognized and adequately treated, monostotic forms almost invariably have a benign prognosis.