Autoimmune encephalitis with anti-NMDAR antibodies in multiple myeloma – case report and literature review

Purpose
The initial presentation of autoimmune encephalitis (AIE) may resemble other disorders and a comprehensive investigation is required. In this paper we emphasize the challenges faced by a treating team performing a differential diagnosis and the necessity for insightful multidisciplinary collaboration.

Case description
We report on the case of a 67-year old man who developed transient disturbances of consciousness in the course of anti-N-methyl-D-aspartate receptor (anti-NMDAR) encephalitis, which was the first manifestation of malignant myeloma. To our knowledge, this is the first case of anti-NMDAR encephalitis associated with multiple myeloma described in the literature.

Comment
AIE with anti-NMDAR antibodies has become a well-characterised variant of the condition. AIE may or may not be associated with tumour; therefore it is necessary to use the screening approach for primary malignancy. A proper diagnosis is essential in management due to AIE’s potential to respond to immunotherapy and tumour removal if one is present.