2017 Volume 31 Issue 1 Pages 46-51
A 63-year-old woman was emergently admitted because of left lower limb myoclonus and gait deficiency. Brain MRI demonstrated diffuse T2 high-intensity foci in the cortex and sub-cortex of the cerebrum, and these enlarged within a 10-day period. Chest CT revealed a mediastinal mass suggestive of thymoma, and the serum level of anti-acetylcholine receptor antibody was elevated. Despite the administration of prednisolone pulse therapy followed by tapering, the neurogenic symptoms and signs of brain dysfunction such as aphasia, muscle weakness, and dementia progressed rapidly. Because the patient had remained immobile in bed, venous thrombosis of the lower limbs occurred. Paraneoplastic neurological syndrome was suspected, and therefore extended thymo-thymectomy was performed on day 31 after admission. The tumor was diagnosed as a type AB thymoma and the WHO pathological staging was pT1N0M0 stage I or Masaoka classification stage I. The neurogenic symptoms and brain dysfunction improved markedly thereafter, and the patient was discharged ambulatory 32 days after surgery following rehabilitation for improvement of the muscle strength.
Paraneoplastic neurological syndrome with a relatively acute onset is considered to be due to an auto-immune reaction against both neurogenic protein and a tumor such as thymoma. Active early treatment of the tumor despite exacerbation of the performance status (PS) is necessary in order to prevent worsening of the neurogenic symptoms.
