Objective:

To report disease characteristics and outcomes in adults > 18 years old with a primary diagnosis of DPPXE presenting as RPD at our institution via retrospective analysis.

Background:

Paraneoplastic syndromes and Immune checkpoint inhibitors (ICIs) are associated with rare but serious neurologic immune-related adverse events, including autoimmune encephalitis (AIE). DPPXE is a rare but treatable AIE. DPPXE manifests as CNS hyperexcitability with subacute memory deficits, confusion, and behavioral changes mimicking RPD clinically, posing a diagnostic challenge. Lack of understanding of disease mechanism, prevalence, associated cancer types and ICI, clinical and paraclinical findings of DPPXE contribute to this diagnostic uncertainty. We aim to study these parameters in a single center retrospective case series to improve DPPXE identification and outcomes.

Design/Methods:

Eligibility includes adults 18+ with DPPXE diagnosis without concurrent diagnoses of other forms of AIE or RPD since March 2016. Retrospective analysis is completed via Epic data pulls using predefined diagnosis of AIE with ICD G04.81 and relevant laboratory codes with non-negative result for DPPX antibodies in serum and/or CSF to screen for patients meeting gold standard DPPXE diagnostic criteria. Demographic, clinical, paraclinical, treatment, and outcome data abstracted via DSC data pull and manual data abstraction such as imaging results and notes are used to confirm patient eligibility by 1 independent reviewer in addition to the authors. 

Results:

451 unique patients with ICD G04.81, and 52/451with laboratory positivity for DPPX antibodies are identified from data pull. Qualitative analyses of clinical, paraclinical, radiologic findings, associated malignancy and immune checkpoint inhibitor use, and treatment outcomes are presented in our study.

Conclusions:

We identify pre-clinical and clinical characteristics of patients with treatable causes of RPD such as DPPXE through our pilot study. The goal is to design best practice from this data and initiate process change in our institution to improve early recognition of treatable causes of RPD.