Paraneoplastic neuropsychiatric syndrome presenting as delirium

Delirium in patients with cancer is associated with poor outcomes, but reversible causes need to be ruled out. We report the case of a 59-year-old woman who was presented with behavioural and cognitive changes over 2 weeks. She was non-verbal and combative, requiring involuntary admission and declaration of incompetence to make healthcare treatment decisions. Infectious and metabolic investigations and initial brain imaging were unremarkable. She was diagnosed with limited-stage small cell lung cancer and a paraneoplastic neuropsychiatric syndrome. Owing to the patient's delirium, chemotherapy delivery required pharmacological and physical restraints. After 2 cycles of chemotherapy, she could participate in the decision process and was discharged home. She completed radical chemo-radiotherapy and has remained free of disease progression for 18 months. Paraneoplastic neuropsychiatric syndromes, although rare, are potentially treatable and need to be excluded as a cause of delirium.