RA-14: LANGERHANS CELL HISTIOCYTOSIS: A PICTORIAL REVIEW

OBJECTIVES: To illustrate the spectrum of imaging findings of Langerhans Cell Histiocytosis in the paediatric population. BACKGROUND/FINDINGS: LCH is a rare multi-systemic group of idiopathic disorders, characterized by the uncontrolled proliferation in different tissues of immunophenotypically and functionally immature histiocytes cells similar to Langerhans cells of the epidermis, including normal inflammatory cells (T cells, eosinophiles, macrophages). Nevertheless, it is a rare disease of unknown cause characterized by an uncontrolled monoclonal proliferation of abnormal Langerhans cells, which can infiltrate almost any organ or tissue. It has a reported annual incidence of 0.2-2.0 cases per 100,000 children. CONCLUSION: Imaging plays an important role in the diagnosis and staging of LCH. The varied nature of bony lesions in both site and appearance as well as the potential for multisystemic involvement makes this an important disease entity for the radiologist to recognise and consider in the differential of both aggressive and non-aggressive bony lesions. Even though imaging features are far from being pathognomonic and diagnosis is based on biopsy results, only imaging findings can provide the true extent and severity of the disease, helping to predict the outcome.