Anti-LGI1-antibody autoimmune encephalitis as a neurological paraneoplastic syndrome associated with gastrointestinal stromal tumour: a case report.

Purpose: The aim of the case is to present the significance of a thorough analysis of the cases of patients with newly developed memory disorders accompanied by epileptic seizures.

Case description: We present a case of a 61-year-old male patient who was admitted to the hospital due to unexplained memory disorders and seizures. Further examination showed the presence of anti-LGI1 (leucine-rich glioma-inactivated 1) antibodies. Computed tomography of the abdominal cavity revealed a mass located between the stomach and the spleen. Histopathological examination identified the mass as a gastrointestinal tumour (GIST). After the surgical removal of the tumour the symptoms were significantly reduced. The early diagnosis and treatment of the tumour contributed to favourable neurological and oncological outcomes for the patient.

Comment: Paraneoplastic neurological syndrome is a clinical condition in which the functioning of the nervous system is impaired, not resulting from local tumour growth or metastases. The currently recognized underlaying mechanism of this condition is an autoimmune reaction occurring in the patient's body. In response to the presence of tumour, the antibodies called onconeural antibodies are produced, which are then directed against antigens present on the nervous system cells. To the best of our knowledge this is the first and so far only anti-LGI1-antibody autoimmune encephalitis as a neurological paraneoplastic syndrome associated with GIST.