058 ANTI-CASPR2-ANTIBODY associated encephalitis in a 63-year old male with chronic lymphocytic leukaemia

Introduction This case from a tertiary neurology centre reports a novel association between the emerging clinical entity of anti-contactin associated protein-2 (CASPR-2) antibody encephalitis and chronic lymphocytic leukaemia (CLL). Case We describe a 63 year old Maori male truck-driver who presented with progressive altered personality, speech, cognition and perception over 9 months. The patient also developed choreiform movements, broad-based gait, incontinence, sleep apnoea with type 2 respiratory failure and episodic loss of consciousness. 12 months prior, he had been diagnosed with low-risk CLL, for which he remained untreated. MRI of the brain revealed mid-sagittal bilateral mid-temporal T2/FLAIR hyperintensities. Cerebrospinal fluid examination showed a mononuclear pleocytosis (WCC 270×10^6/L) with 15% of these CD5/CD19/CD23 positive and 92% CD3/CD5 positive CD 19 negative on flow cytometry, protein was also elevated at 2600 mg/L. The interplay between CLL and inflammation is uncertain. Anti-Caspr2-antibody was identified in CSF and serum. The patient was treated with a combination of fludarabine, cyclophosphamide, rituximab, dexamethasone and intravenous immunoglobulin (IVIG). Clinical status improved and antibody titre decreased from 580 to 241 pM in three weeks and to 55pM (negative Conclusion Whilst paraneoplastic VGKC encephalitis has been described associated with a number of malignancies, this is the first reported case of CASPR-2 antibody present in association with CLL. References . Van Sonderen A, Petit-Pedrol M, Dalmau J, Titulaer MJ. The value of LGI1, Caspr2 and voltage-gated potassium channel antibodies in encephalitis. Nature Reviews Neurology2017;13(5):290–301. . Nogai H, Israel-Willner H, Zschenderlein R, Pezzutto A. Improvement in Paraneoplastic Limbic Encephalitis after Systemic Treatment with Rituximab in a Patient with B-Cell Chronic Lymphocytic Leukaemia. Case Reports in Haematology2013;2013:Article ID958704. . Van Sonderen A, Arino H, Petit-Pedrol M, et al. The Clinical Spectrum of Caspr2 antibody-associated disease. Neurology2016;87:521–528. . Gultekin SH, Rosenfeld MR, Voltz R, Eichen J, et al. Paraneoplastic limbic encephalitis: Neurological symptoms, immunological findings and tumour association in 50 patients. Brain2000;123:1481–1494.