Solitary tibial lesion as the initial presentation of Langerhans cell histiocytosis: report of two cases and literature review

The various presentations of osseous Langerhans cell histiocytosis (LCH) make it difficult to distinguish from other bone diseases. In addition, there is no universally accepted protocol for managing osseous LCH for single non-central nervous system-risk lesions. Here, the rare cases of two paediatric patients, aged 1 and 2 years, who presented with a solitary tibial lesion at time of LCH diagnosis, are reported. One patient progressed to multiple lesions after curettage of the original lesion. Subsequently, both patients received preventive chemotherapy using the Taiwan Paediatric Oncology Group (TPOG) revised protocol for treating low risk patients with LCH, namely, TPOG LCH2002-LR. After receiving this treatment, which included a schedule of prednisolone and vincristine for 6 weeks, followed by prednisolone, vincristine and 6-mercaptopurine for a further 48 weeks, both patients are free from recurrence or progression.