Background Chorea is a hyperkinetic movement disorder characterised by involuntary, unpredictable muscle contractions and is associated with a broad range of primary and secondary aetiologies.

Case A 73-year-old gentleman presented with a 12 month history of progressive behavioural change and involuntary movements. His family had become concerned about periods of erratic behaviour and confusion. He appeared agitated and restless. On examination he had choreiform movements predominantly affecting his upper limbs. An abnormal diastolic heart sound was detected on auscultation.

MRI brain and CSF analysis were normal; ASO titre, paraneoplastic, anti-NMDAr antibodies and Huntington’s genetics were negative. A blood film was normal. Transoesophageal echocardiogram demonstrated a variegated mobile mass within the left atrium.

An immune-mediated mechanism was suspected. Intravenous immunoglobulins and oral corticosteroids were trialled with initial major benefit but he relapsed several months later and did not respond to a further trial. The atrial mass was resected and histological analysis confirmed an atrial myxoma. The chorea and cognitive symptoms significantly improved after surgery and he remains well.

Discussion Atrial myxoma is the most common primary tumour of the heart and is rare with an incidence of 0.5/1,000,000 population/year. There has only been one other case in the paediatric literature.