# Where There's Smoke, There's Fire: Paraneoplastic Autoimmune Limbic Encephalitis

## TL;DR

This paper presents a case of paraneoplastic autoimmune limbic encephalitis linked to small cell lung cancer, highlighting the diagnostic challenges in patients with subtle neurological symptoms.

## Contribution

The novelty lies in illustrating a rare but important connection between neurological symptoms and underlying cancer through a detailed case study.

## Key findings

- The patient's neurological symptoms were later linked to small cell lung cancer.
- Initial screening assessments were unremarkable, complicating the diagnosis.
- The case emphasizes the need for thorough evaluation in patients with new neurological signs.

## Abstract

Autoimmune encephalitis can be stemmed from paraneoplastic, drug-induced, post-infectious, and idiopathic etiologies. It is often but not always associated with neuronal cell surface or intracellular antigens. Regarding encephalitis in the limbic system, the patients mostly present with impairment of cognitive functions with subacute presentation, changes in personalities, memory loss, and seizures. We present a case of a patient who presented with subtle neurological symptoms and later progressed to refractory focal epileptic activities, posing a characteristic sign of limbic encephalitis. He was later diagnosed with small cell lung cancer on further workup. This case poses a classical yet challenging diagnostic puzzle alongside education on how to disentangle patients presenting with de novo neurological signs and symptoms with unremarkable initial screening assessments and investigations in acute settings.