Managing paraneoplastic GABABR-related limbic encephalitis in a patient with a small cell lung cancer receiving an Immune-Checkpoint Inhibitor (ICI) therapy: description of a case report.

INTRODUCTION

GABAB receptor (GABABR)-related paraneoplastic limbic encephalitis (PLE) is frequently associated with cancer, particularly small cell lung carcinoma (SCLC) and shows several clinical presentations often accompanied by distinctive MRI and EEG findings. It can be exacerbated by immune-modulating therapies, such as immune checkpoint inhibitors (ICIs) and needs a multidisciplinary approach.

CASE REPORT: This case report describes a 67-year-old male with a diagnosis of SCLC who developed a paraneoplastic LE. The patient's clinical presentation included amnesia, apraxia, and mesial temporal lobe seizure. MRI showed bilateral hippocampal involvement, and cerebrospinal fluid analysis revealed elevated protein levels and GABAB-R antibodies confirming the diagnosis of PLE. Despite the initial treatment with high-dose corticosteroids and intravenous immunoglobulins, the patient's neurological symptoms persisted, prompting the addition of plasmapheresis and rituximab that led to a slight clinical improvement. Considering this modest activity and the elevated IL-6 levels in the cerebrospinal fluid, we added a treatment by tocilizumab that allowed a full neurological recovery.

DISCUSSION AND

CONCLUSION

This case highlights the difficulty and complexity of the diagnosis and management of this rare entity, particularly in cancer patients receiving ICIs. This report suggests also the potential efficacy of combining rituximab and tocilizumab and clearly demonstrates that a multidisciplinary approach, tailored to individual patient's response, is crucial for optimizing treatment outcome.