[Successful treatment of Erdheim-Chester disease by 2-chlorodeoxyadenosine-based chemotherapy. Two case studies and a literature review]

Erdheim-Chester disease is an extremely rarely occuring condition and thus an optimal treatment is not known. Two new cases have been diagnosed in our centre in 2008 and 2009. Both patients had diabetes insipidus, B symptoms (subfebrile to febrile states) and pain in long bones of lower limbs.

Imaging showed high accumulation of fluorodeoxyglucose as well as Tc-pyrophosphate in long bones of lower as well as upper limbs, aortic wall thickening with periaortic fibrosis and perirenal fibrosis. In addition, one of the patients had multiple lesions in the brain. 2-chlorodeoxyadenosine 5 mg/m2 s.c. and cyclophosphamide 150 mg/m2 administered on days 1 to 5 in 28-day cycles were selected for the treatment of both patients. Dexamethasone 24 mg/day for 5 days was added to this treatment in the second patient. Six cycles of the treatment were planned. Both patients were prescribed bisphosphonates--zoledronate and clodronate, respectively. Treatment effect was assessed with PET-CT and MR. Following treatment completion, brain infiltrates were reduced to a small residuum in the first patient who did not anymore complain of leg pain. However, there was no reduction in fluorodeoxyglucose accumulation in bone lesions and thus treatment response was assessed as partial remission. This patient is currently receiving a second line treatment and treatment follow-up is 26 months from the diagnosis. Repeated PET-CTs in the second patient showed a significant reduction in accumulation of fluorodeoxyglucose in all pathological lesions. Febrile states and pain in long bones as well as pathological fatigue ceased after the treatment. Increased CPR and fibrinogen gradually returned to their normal levels. This response is assessed as complete remission. This patient's follow-up is 16 months from the diagnosis.

Administration of 2-chlorodeoxyadenosine (5 mg/m2 s.c.) + cyclophosphamide (150 mg/m2 intravenously) and dexamethasone (24 mg/day) led to partial remission in one patient; nearly complete remission of CNS infiltrates but persistent elevation of fluorodeoxyglucose accumulation in bone lesions. Complete remission with a significant reduction in accumulation of fluorodeoxyglucose in all disease lesions with normalization of originally increased inflammatory markers and disappearance of all symptoms of the disease was achieved in the second patient.