Misdiagnosis: CNS Erdheim-Chester disease mimicking CLIPPERS

Introduction Chronic lymphocytic inflammation with pontine perivascular enhancement responsive to steroids (CLIPPERS) is an inflammatory central nervous system (CNS) disorder with particular involvement of the pons. Diagnostic criteria include a range of clinical symptoms related to the underlying brainstem pathology, visible with magnetic resonance imaging (MRI). MRI findings include the appearance of punctuate and curvilinear gadolinium enhancement 'peppering' the pons. We discuss a patient presenting with clinical and radiographic characteristics of CLIPPERS who was diagnosed with Erdheim-Chester disease (ECD). Case report A 52-year-old male presented with 2 years of progressive spasticity, dysarthria, and gait instability. Initially, he was diagnosed with Parkinson's disease at an outside hospital, based on tremor, rigidity, and gait instability; however, he failed to improve with a trial of levodopa. Brain MRI showed small enhancing parenchymal nodules coalescing in the central pons, but also affecting the cerebellum and cerebellar peduncles, with more punctate enhancing lesions in the cerebral lobar subcortical white matter. When the patient's response to steroids was inadequate, further imaging was done, revealing perinephric processes. Subsequent biopsy revealed ECD. Conclusions A review of the literature for cases of CLIPPERS demonstrated a subset of patients later found to have various malignancies involving the CNS. This case report uses the patient's unique radiographic and clinical presentation to demonstrate the importance of the exclusion criteria within the CLIPPERS diagnostic requirements and stresses red flags suggestive of alternative diagnoses. This distinction is of high importance when differentiating a relatively benign process such as CLIPPERS from more malignant diseases.