ESPE Abstracts

Langerhans cell histiocytosis (LCH) represents a spectrum of rare disorders characterised by idiopathic infiltration and accumulation of abnormal histiocytes (i.e. the Langerhans cells) within various tissues. Bone is the most frequently affected tissue in children with LCH, with unifocal involvement being more common than multifocal involvement. Some of these lesions can cause severe pain and lead to pathological fractures. We describe a case series of 2 patients who had received bisphosphonates for LCH with resolution of bone pain. One had lesions in her skull and left tibia. Another had mono-ostotic lesion at his left tibia. Both have resolution of their bony lesions on imaging. Bisphosphonates can be considered as a monotherapy for mono-ostotic and polyostotic bony lesions in LCH, resulting in remission of the disease without need for other chemotherapeutic agents. It is well tolerated, significantly improves bone pain and can induce remission in active bone lesions. We reviewed the literature for use of bisphosphonates in LCH and the various dosing regimen. 12 of 13 patients (92%) achieved resolution of active bone lesions, and 10 out of them had no active disease for a median of 3.5 years (range, 0.8 to 5 years).