Abstract
ObjectivesThe aim of this study was to [1] characterize distribution of Erdheim-Chester Disease (ECD) by 18F-FDG PET/CT and [2] determine the utility of metabolic (18F-FDG PET/CT) imaging versus anatomic imaging (CT or MRI) in evaluating ECD patients for clinical trial eligibility.Methods18F-FDG PET/CT and corresponding CT or MRI studies for ECD patients enrolled in a prospective registry study were reviewed. Sites of disease were classified as [1] detectable by 18F-FDG PET only, CT/MRI only, or both and as [2] measurable by modified PERCIST (mPERCIST) only, RECIST only, or both. Descriptive analysis was performed and paired t test for between-group comparisons.ResultsFifty patients were included (mean age 51.5 years; range 18–70 years). Three hundred thirty-three disease sites were detected among all imaging modalities, 188 (56%) by both 18F-FDG PET and CT/MRI, 67 (20%) by 18F-FDG PET only, 75 (23%) by MRI brain only, and 3 (1%) by CT only. Of 178 disease sites measurable by mPERCIST or RECIST, 40 (22%) were measurable by both criteria, 136 (76%) by mPERCIST only, and 2 (1%) by RECIST only. On the patient level, 17 (34%) had mPERCIST and RECIST measurable disease, 30 (60%) had mPERCIST measurable disease only, and 0 had RECIST measurable disease only (p < 0.0001).ConclusionCompared with anatomic imaging, 18F-FDG PET/CT augments evaluation of disease extent in ECD and increases identification of disease sites measurable by formal response criteria and therefore eligibility for clinical trials. Complementary organ-specific anatomic imaging offers the capacity to characterize sites of disease in greater anatomic detail.Trial registrationClinicalTrials.gov Identifier: NCT03329274
Highlights
Erdheim-Chester disease (ECD) is a rare and clinically heterogeneous non-Langerhans cell histiocytosis with about 1000 reported cases to date [1]
Remarkable advances have been made in the understanding of the pathogenesis of ECD with the discovery of recurrent BRAFV600E and other activating mitogen-activated protein kinase (MAPK) pathway mutations in ECD tissue [5,6,7,8]
In 39 patients, a whole-body 18F-FDG positron emission tomography/computed tomography (PET/CT) including the brain and legs was performed, and in 11 patients, the examination ranged from skull base to thighs
Summary
Erdheim-Chester disease (ECD) is a rare and clinically heterogeneous non-Langerhans cell histiocytosis with about 1000 reported cases to date [1]. ECD diagnosis is made by a combination of clinical, radiologic, and pathologic findings; biopsy of lesional sites frequently demonstrates xanthomatous histiocytes, with the non-Langerhans immunophenotype of being CD68+, CD1a- and CD207- with admixed inflammation and fibrosis. ECD patients present a tremendous burden of generalized and focal symptomatology [14, 17]. They frequently have concomitant diagnoses that could independently produce symptoms, such as autoimmune disease [18] and other neoplasms [19]; identification of ECD lesional sites is important to differentiate symptoms of infiltrative disease versus non-ECD symptoms. Identification of ECD sites of disease may determine eligibility for clinical trials and provide evaluable target lesions for response assessment
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