Aggressive unifocal bone Langerhans cell histiocytosis with soft tissue extension both responsive to radiotherapy: a case report.

Background: Langerhans cell histiocytosis (LCH) is a rare haematological neoplasm characterized by the accumulation of CD1a, CD207/Langerin histiocytes within inflammatory lesions. LCH can involve any organ, but osteolytic bone lesions are most often encountered. Unifocal bone lesions may regress spontaneously after a thick needle biopsy has been taken.