Reversible extralimbic paraneoplastic encephalopathies with large abnormalities on magnetic resonance images

Objective: To describe reversible extralimbic paraneoplastic encephalopathies with large, lobar lesions on magnetic resonance imaging (MRI). Design: Case series. Setting: Autoimmune Neurology Clinic, Mayo Clinic, Rochester, Minnesota. Results: Three patients had large confluent areas of signal abnormality on T2-weighted MRI, including frontal in 2 and frontal and occipital in 1. Patient 1, a woman aged 63 years, experienced hemiparesis with hemianopia 3 years after a diagnosis of adenocarcinoma of the breast. Nine years later, rapidly progressive dementia developed. Patient 2, a woman aged 79 years, presented with monoparesis and epilepsia partialis continua, 1 year after a diagnosis of adenocarcinoma of the breast. Patient 3, a man aged 65 years, had paraneoplastic sensory neuronopathy, limbic encephalitis, antineuronal nuclear autoantibody type 1 (ANNA-1), and squamous cell carcinoma of the lung. He was stable for 3 years after treatment. Subacute onset of aphasia, delirium, worsening seizures, and rising ANNA-1 titers led to a diagnosis of recurrent limited carcinoma. Brain MRI abnormalities in all patients improved dramatically after immuno-therapy. Two patients had sustained clinical remission. Conclusion: Recognition of paraneoplastic extralimbic lobar encephalopathies is important because these disorders and their underlying cancers are treatable.