2764 A case of semantics: huntington disease presenting as primary progressive aphasia

ObjectiveWe present a case of the semantic variant of primary progressive aphasia (PPA) as the initial presenting feature in a patient with Huntington disease (HD).CaseA 76-year-old Caucasian man was referred for evaluation of progressive language impairment, including impaired naming, object knowledge and single word comprehension consistent with the semantic variant of PPA. He subsequently developed behavioural changes and a hyperkinetic movement disorder, characterised by frank choreiform movements of the upper limbs, trunk, and lower limbs with oromandibular dyskinesia and motor impersistence of tongue protrusion. Magnetic resonance imaging (MRI) of the brain showed left anterior temporal lobe and hippocampal atrophy. A neurological FDG PET-CT showed reduced metabolism in the head of the left caudate nucleus. HTT gene testing revealed an expansion of 39 CAG repeats in one allele.ConclusionThe case outlines the substantial overlap between the clinical presentation of HD and frontotemporal lobar degeneration (FTLD) syndromes. Genetic testing in this case supported the diagnosis of atypical HD, presenting with semantic variant PPA.