Usefulness of nuclear medicine in Erdheim-Chester disease: A Lille experience

Introduction. - Erdheim-Chester disease is a rare form of non-langerhans histiocytosis and its etiology is still not well established. The aims of the study were to assess the value of the bone scintigraphy and the 18F-FDG PET/CT for the diagnostic and for the latter in the therapeutic evaluation. Methods. - We retrospectively reviewed 49 patients suspected of Erdheim-Chester disease between 2004 and 2016. Bone scintigraphy was compared with histopathology and PET-CT to conventional morphological examinations and bone scintigraphy. For therapeutic evaluation, thresholds similar to PERCIST 1.0 were used. Results. - Forty-nine bone scintigraphy were evaluated with a sensitivity of 100%, a specificity 97%, a positive predictive value 90% and a negative predictive value of 100%. Eight patients had at least an initial PET-CT. The sensitivity compared to conventional morphological examinations differed from the location but was excellent for orbital, bone and vascular involvements. Specificity was comparable between the different examinations. Six patients treated-with interferon (R) and three with vemurafenib (R) were followed by PET-CT. PET-CT, in agreement to clinicobiological data, identified 4 partial responses and one complete response with interferon (R) et two partial responses and one complete response with vemurafenib (R). Conclusion. - Our retrospective study suggests that bone scintigraphy and 18F-FDG PET/CT could be useful in the initial assessment of Erdheim-Chester disease but also for the latter in the therapeutic evaluation. (C) 2016 Societe Nationale Francaise de Medecine Interne (SNFMI). Published by Elsevier Masson SAS. All rights reserved.