From classical Langerhans cell histiocytosis to Erdheim-Chester disease: different sides of the same coin?

Abstract

Objective. Analysis of the clinical course of classical histiocytosis (LCH) in children and clinical differences, diagnostic difficulties and a different therapeutic strategy in a child with a rare variant of LCH in the form of Erdheim-Chester syndrome (ECD). Patients and methods. Retrospective single-center analysis of the clinical course of classic LCH in 54 children who were diagnosed with the disease in the last 40 years and the differences shown in a patient with diagnosed EDC. The clinical response was assessed according to the LCH programs valid at the time for the classic form of LCH and in the child with ECD. Results. The multi-system form of LCH was diagnosed more often than the single-system form. The skull bones were the most common localization of LCH in both forms of the disease. Recurrence of the disease occurred in about 5% of patients, death in one (1.9%) patient. The course of the child with ECD was more turbulent, with rapid progression, involvement of critical organs, no response to standard chemotherapy according to the LCH 2009 protocol. After the molecular diagnosis was specified, therapy with vemurafenib, a BRAF-V600E kinase inhibitor, followed by transplantation of hematopoietic stem cells (allo-HCT) was applied. Basic disease was in remission and lasts for 12 months. Conclusions. The lack of an expected response to LCH therapy should indicate the possibility of rare forms of histiocytic hyperplasia. Molecular tests are an important element in the diagnosis of histiocytosis and allow to precisely select the most appropriate, targeted therapy. BRAF-V600E kinase inhibitors are highly safe and effective in the treatment of LCH and ECD with a confirmed BRAF-V600E mutation, however allo-HCT should be considered in selected cases.