Paraneoplastic limbic encephalitis (PLE) is a rare autoimmune neurological syndrome, characterised by the development of neuropsychiatric symptoms and associated with cancer in the absence of tumour cell invasion of the nervous system. PLE is often seen in small-cell lung cancer (SCLC), but can also be found in other cancers, such as breast cancer, thymoma, ovarian teratoma and Hodgkin lymphoma. The course of most PLEs is subacute and symptoms occur before the detection of tumour. The diagnosis of PLE is still mainly based on clinical manifestations and antibody tests, rather than imaging. The identification of specific circulating autoantibodies in patients has revolutionised the diagnosis of PLE and demonstrated immune system involvement.1,2 We present the case of a 62-year old female patient, with history of left sided breast cancer, who presented in 2018 with fatigue, hallucinations, confusion, sleep disorders and anterograde amnesia. Further workup included brain magnetic resonance imaging (MRI) which suggested a diagnosis for limbic encephalitis. Serum and cerebrospinal fluid (CSF) Anti-Hu, anti-Sox1 and anti-Zic4 antibodies were positive. A positron emission tomography – computed tomography (PET-CT) scan revealed two mediastinal lymph nodes and the biopsy of one of them was positive for a small cell carcinoma. In conclusion, paraneoplastic limbic encephalitis occurs at an early stage of the disease development and its detection can therefore lead to an earlier identification of the underlying malignancy and subsequently to a better outcome.

(BELG J MED ONCOL 2020;14(6):293-6)