Autoimmune gastrointestinal dysmotility due to small cell lung cancer.

The diagnosis of autoimmune gastrointestinal dysmotility requires a high level of clinical suspicion when standard work-up is unrevealing. We report the case of a 56-year-old male patient with history of tobacco use and a subacute presentation of weight loss, vomiting and cerebellar ataxia. The discovery of paraneoplastic type 1 antineuronal nuclear antibodies and neuronal acetylcholine receptor antibodies led to further directed imaging and diagnostic studies in spite of prior negative chest imaging. Bronchoscopy with endobronchial ultrasound was used to confirm a diagnosis of small cell lung cancer and paraneoplastic syndrome as the cause of the presenting upper gastrointestinal symptoms.