Nicotinic ganglionic acetylcholine receptor autoantibodies associated with paraneoplastic disease in a neuropsychiatric patient.

Nicotinic ganglionic acetylcholine receptor autoantibodies (alpha-3-AChR Ab) are associated with paraneoplastic syndromes when present in low elevations. These antibodies can be tested for as part of an autoimmune encephalopathy panel in neuropsychiatric patients; a mildly elevated titre of alpha-3-AChR Ab that may start as an incidental finding can lead to the diagnosis of a previously undetected cancer. While alpha-3-AChR Ab are most typically associated with thymomas and small cell lung cancer, the presence of these antibodies can suggest a diverse range of other cancers. This case presents a patient with longstanding neuropsychiatric symptoms and possible functional hypothyroidism for whom a low elevation in alpha-3-AChR Ab led to the finding of papillary thyroid carcinoma.