Thymoma-associated paraneoplastic encephalitis resolved by robotic-assisted radical thymectomy: a case report

We present a rare case of autoimmune encephalitis associated with an incidentally discovered thymoma. Limited case reports exist of thymoma-associated paraneoplastic encephalitis. The unique clinical presentation and subsequent surgical intervention offer valuable insights into the management of similar cases.

A 41-year-old female presented with irritability, personality changes, fatigue, and seizures. Physical examination and bloodwork on first encounter were unremarkable. Neurological evaluation was done, and a brain magnetic resonance imaging (MRI) with and without contrast demonstrated numerous hyperintensity foci within bilateral cerebral cortices on T2-/FLAIR-weighted images affecting only the supratentorial brain, findings highly suggestive of encephalitis. A chest computed tomography (CT) revealed an anterior mediastinal mass compatible with a thymoma. Cerebrospinal fluid from a lumbar puncture was unremarkable. Paraneoplastic autoantibody evaluation was positive, and the patient was diagnosed with autoimmune encephalitis believed to be associated with an incidentally discovered thymoma. Given her rapid neurological deterioration, the thoracic surgery team was urgently consulted.

Patient underwent robotic-assisted radical thymectomy with prompt resolution of symptoms. During her 2-week postoperative visit, she was neurologically intact with no residual deficits. Follow-up MRI at 6 months demonstrated resolution of abnormal signal intensities, with continued improvement noted 1-year post-operation. Chest CT scans at 6 and 12 months revealed no residual or recurrent thymic tissue.

This case illustrates the connection between thymoma and autoimmune neurological disorders like encephalitis. It emphasizes the significance of comprehensive neurological and oncological assessments for patients with unexplained neurological symptoms. Prompt diagnosis and treatment led to positive outcomes in this case, underscoring the potential for full recovery in similar cases.