Abstract Details

ECD is a histiocytic neoplasm characterized by multiorgan infiltration of clonal histiocytes carrying activating mutations of MAPK-ERK pathway. Neurologic involvement occurs in up to 40% of ECD with frequent brainstem lesions that mimic acquired neuroinflammatory disorders, such as CLIPPERS.

To present four patients with Erdheim-Chester Disease (ECD) based on clinical, radiologic, histopathologic, and molecular genetic findings presenting with a chronic lymphocytic inflammation with pontine perivascular enhancement responsive to steroids (CLIPPERS)-like syndrome.

Case series.

While patients with ECD can demonstrate clinical and imaging features similar to CLIPPERS, refractoriness to corticosteroids, lack of fulfillment of specific MRI criteria (enhancing lesions > 3mm, T2 abnormalities that exceed areas of T1 post-gadolinium enhancement), and systemic findings such as “hairy kidney” appearance and meta-diaphyseal osteosclerosis on ¹⁸F-fluorodeoxyglucose positron emission tomography computed tomography [¹⁸F-FDG PET-CT] help discriminate it from CLIPPERS.

ECD is an important CLIPPERS mimic with distinct pathophysiology and targeted treatments. We highlight the need to consider histiocytic disorders among other alternate diagnoses when findings are not classic for CLIPPERS.