A case report of limbic encephalitis in a metastatic colon cancer patient during first-line bevacizumab-combined chemotherapy.

Rationale: Paraneoplastic limbic encephalitis (PLE) is one of the most common causes of neurologic paraneoplastic syndromes, with unclear pathogenesis. While several reports published in the last decades showed the occurrence of PLE in a variety of cancers, only a few cases have been associated with colon cancer.

Patient Concerns: In February 2017, a 54-year-old man with clinical history of radically resected colon cancer started first line chemotherapy with FOLFOXIRI plus bevacizumab, after radiological diagnosis of multiple liver and bone metastases. During the third cycle of treatment, the patient developed psychomotor agitation and hallucinations followed by severe consciousness level reduction and cognitive impairment.

Diagnoses: Magnetic resonance imaging showed hyperintense signals in both hippocampal areas, insula and right cingulate gyrus on fluid attenuated inversion recovery, diffusion weighted imaging, and T2-weighted images, highly suggestive of limbic encephalitis. Other causes (brain metastases, toxicity of chemotherapeutic agents, and infections) were excluded.

Interventions: Empirical immunosuppressive treatment (high-dose immunoglobulins and corticosteroids) was administered and chemotherapy was resumed.

Outcomes: A slowly progressive improvement in neurological condition has been observed, even though radiological signs of limbic encephalitis are still evident.

Lessons: The present case highlights the complex diagnostic process of PLE, and the lack of a standard treatment. Moreover, the absence of correlation between PLE and tumor progression or tumor burden, and the opportunity of treating underlying neoplasm is discussed.